English

• 1.   Introduction

  Organotin compounds, an very important class of organometallic compounds, have been intensively applied in organic synthesis because of their good stabilities towards heat, hydrolysis and oxidation, tolerance of functional groups and high selectivity in organic reactions.^[1] However, most of the organotin compounds are toxic, and are not atom economic in the reactions.^[2] For instance, the commonly used tributyltin compounds Bu₃SnR can only transfer the R groups into the product molecules, meanwhile, the Bu₃Sn-moiety is discarded as a by-product.^[3] This disadvantage limits their application on large scale in industrial. In 1981, Mukaiyama et al.^[4] reported for that tin powder could promote the allylation of aldehydes or ketones with allyl bromide to give the corresponding allylic alcohols. This method not only keeps the advantages of organotin reagents but also avoids some of their disadvantages. Afterwards, many studies on tin-powder-promoted allylations were carried out. Up to now, tin-powder-promoted allylation reactions mainly involve the 1, 2-addition reactions of aldehydes, ketones and imines with in situ generated allyltin bromide.^[5] (Schemes 1a and 1b). Enol ethers and nitroalkenes were also used as substrates to react with allyl bromide in the presence of tin powder, but the active intermediates were still the in situ generated aldehydes or ketones.^[5] Diselenides and disulfides were reported to perform the allylation with allyl bromide and tin powder^[7] (Scheme 1c). In view of the advantages of tin-powder-promoted reactions, our group has been committed to the allylation reactions promoted by tin powder, and a series of allylic compounds and nitrogen heterocycles were synthesized.^[8] These works greatly extend the application of tin-powder- promoted reactions in organic synthesis. However, until now, tin-powder-promoted reactions mainly limited to the allylation of C＝O or C＝N double bounds, and there was no report to the other functional groups. In our research works, we find that the in situ generated allyltin bromides are stable in solid state in the absence of solvent. We envision that this property would make them to react with other functional groups, and extend the tin-powder-promoted reactions beyond 1, 2-addition to C＝O or C＝N double bounds. As we know, carbocations are very important active intermediates in organic reactions and have always played important roles in organic synthesis.^[9] In the carbocation family, benzylic carbocations are relatively stable and easily formed. Therefore, we would like to investigate the C—C coupling reaction of solid allyltin bromide with in situ formed benzylic carbocations. Herein, the reaction of 3-aryl-3-hydroxy-2-oxindoles with the in situ formed allyltin bromide to afford 3, 3-disubstituted-2-oxindole derivatives (Scheme 1d) was reported.

  Scheme 1

  

  Scheme 1.  Allylation reaction promoted by tin powder

  下载: 全尺寸图片 幻灯片

  2.   Results and discussion

  In our initial investigations, a mixture of tin powder (3.5 equiv.) and allyl bromide (3.0 equiv.) in tetrahydrofuran (THF) was refluxed for 5 h, and then the solvent was evaporated off under vacuum to give a white solid residue, which was re-dissolved in 4 mL of dichloromethane (DCM). 3-(p-Methoxylphenyl)-3-hydroxy-2-oxindole (1a, 1 equiv.) and BiCl₃ (0.1 equiv.) were added to the mixture. After stirring the mixture at room temperature for another 5 h, the product 3a was obtained in 47% yield and by-product 4a was obtained in 20% yield (Table 1, Entry 1). In order to improve the product yield, the effects of other typical Brönsted acids and Lewis acids on the reaction were investigated. First, Fe(OTf)₃, Cu(OTf)₂, and HClO₄ were found to be equally effective to the reaction (Table 1, Entries 2~19). In consideration of the cost, HClO₄ was used to check the other reaction parameters. Thus, the amount of HClO₄ was then increased to 1 equiv., and the yield of 3a reached 58% (Table 1, Entry 20). Afterwards, the influence of the molar ratio of the starting materials on the product yield was examined (Table 1, Entries 20~22). It was found that the yield of 3a increased to 87% when the molar ratio of 1a/2/Sn reached 1.0/4.0/4.5. Finally, the effects of solvents on the reaction were screened, and DCM was found to be the suitable solvent (Table 1, Entries 23~28). Other solvents such as DCE, CH₃CN and THF gave the products in medium yields, methanol and ethanol did not afford separable product. Therefore, the optimized reaction conditions were the use of 1a, 2 and tin powder in a molar ratio of 1:4.0:4.5 in DCM at room temperature (Table 1, Entry 21).

  表 1

  

  表 1  Optimization of the reaction conditions^a

  下载: 导出CSV

  Entry	Molar ratio of 1:2:Sn	Solvent	Acidb	Yieldc/%
  				3a	4a
  1	1.0:3.0:3.5	DCM	BiCl3	47	20
  2	1.0:3.0:3.5	DCM	FeCl3	0	0
  3	1.0:3.0:3.5	DCM	Fe(OTf)3	47	3
  4	1.0:3.0:3.5	DCM	InCl3	25	1
  5	1.0:3.0:3.5	DCM	In(OTf)3	33	2
  6	1.0:3.0:3.5	DCM	Ni(ClO4)2•6H2O	Trace	0
  7	1.0:3.0:3.5	DCM	NiCl2•6H2O	Trace	0
  8	1.0:3.0:3.5	DCM	Ni(OTf)2	6	1
  9	1.0:3.0:3.5	DCM	Mg(ClO4)2	19	0
  10	1.0:3.0:3.5	DCM	BF3•OEt2	5	Trace
  11	1.0:3.0:3.5	DCM	Sc(OTf)3	13	1
  12	1.0:3.0:3.5	DCM	Cu(OTf)2	47	4
  13	1.0:3.0:3.5	DCM	Yb(OTf)3	25	2
  14	1.0:3.0:3.5	DCM	TfOH	38	1
  15	1.0:3.0:3.5	DCM	H2SO4	40	2
  16	1.0:3.0:3.5	DCM	H3PO4	38	3
  17	1.0:3.0:3.5	DCM	HNO3	29	4
  18	1.0:3.0:3.5	DCM	HCl	35	3
  19	1.0:3.0:3.5	DCM	HClO4	46	1
  20	1.0:3.0:3.5	DCM	HClO4	58	0
  21	1.0:4.0:4.5	DCM	HClO4	87	0
  22	1.0:5.0:5.5	DCM	HClO4	82	0
  23	1.0:4.0:4.5	DCE	HClO4	65	0
  24	1.0:4.0:4.5	CH3CN	HClO4	54	3
  25	1.0:4.0:4.5	THF	HClO4	69	0
  26	1.0:4.0:4.5	1, 4-Dioxane	HClO4	85	0
  27	1.0:4.0:4.5	CH3OH	HClO4	Trace	0
  28	1.0:4.0:4.5	CH3CH2OH	HClO4	Trace	0
  a All reactions were carried out by using 0.3 mmol of 1a, 0.9~1.2 mmol of 2, 1.05~1.35 mmol of tin powder, 0.03~0.3 mmol of acid in 4 mL of solvent at room temperature for 10 h; bAcid: Entries 1~19, 10 mol%; Entries 20~28, 100 mol%; c Isolated yields.

  With the optimum reaction conditions in hand, the substrate scopes were examined. At first, the effects of the substituents on the benzene ring and nitrogen atom of the oxindole core were examined by using 3-(p-methoxyl-phenyl)-3-hydroxy-2-oxindoles (1) as substrates. The results indicated that the position of the substituents on the benzene ring of the oxindole core did not influence the reaction too much. For instance, the difference among products 3e, 3f and 3g was the position of chlorine atom on the benzene ring of the oxindole core, but their yields were around 70% (Table 2, 3e, 3f and 3g). The electronic properties of the substituents had a little bit of influence on the product yields. For example, the oxindoles 1 with the electron-donating groups on the phenyl ring of the oxindole core gave the corresponding products in higher yields than those with electron-withdrawing ones (Table 2, 3b and 3c vs. 3d~3i). The protecting groups on the nitrogen atom of the oxindoles 1 did not influence the product yields too much (Table 2, 3j~3p). However, when t-butyloxycar-bonyl group was used as protecting group, it would be deprotected after the reaction (Scheme 2).

  Scheme 2

  

  Scheme 2.  Allylation of tert-butyl 3-hydroxy-3-(4-methoxyphenyl)-2-oxoindoline-1-carboxylate

  下载: 全尺寸图片 幻灯片

  表 2

  

  表 2  Substrate scope of allylations using 3-hydroxy-2-oxindoles 1^a

  下载: 导出CSV

  To further investigate the generality of the substrates, the substituents R³ at 3-position of 3-hydroxy-2-oxindoles were varied. As shown in Table 3, when R³ was 3-indolyl group, the products 6a~6k obtained in good yields under the standard conditions. The electronic properties of the substituents on benzene ring of 3-indolyl groups had influence on the product yields. When the substituents were electron-donating groups, the product yields were higher than the electron-withdrawing ones (Table 3, 6b and 6c vs. 6d). However, when the R³ groups were benzene groups, the substituents on the benzene rings had a great influence on the product yields. For instance, if the R³ was just benzene ring, the product 6p did not be obtained (Table 3, 6p). When the R³ was p-methylphenyl group, the product 6l obtained in 58% yield. When 3-(3, 4-dimethoxyphenyl)-3-hydroxyindolin-2-one was used as substrate, the yield of 6m reached to 85%. The results from 6l~6p indicated that the more electron-donating substituents on the benzene rings of R³ were, the higher the product yields would be. Finally, the aliphatic R³ groups such as allyl and methyl groups were examined, but no corresponding products were formed (Table 3, 6q and 6r).

  表 3

  

  表 3  Substrate scope of allylations using 3-hydroxy-2-oxindoles 5^a

  下载: 导出CSV

  In order to further expand the application of the reaction, the benzyl alcohols such as 1-phenylethan-1-ol and diphenylmethanol have been investigated. As shown in Scheme 3, when diphenylmethanol was used as substrate, the reaction took place smoothly and the product 8b was obtained in 48% yield; when 1-phenylethan-1-ol was used as substrate, the reaction did not occur.

  Scheme 3

  

  Scheme 3.  Reaction of benzyl alcohols as substrate

  下载: 全尺寸图片 幻灯片

  Based on the above results and previous reports, ^[10] a tentative reaction pathway for the carbocations 9 was proposed as depicted in Scheme 4. 3-Hydroxy-2-oxindoles (1 or 5) were protonated to afford the intermediate 10, which dehydrated to give the carbocations 9. Nucleophilic attachment of in situ formed organotin reagents 11 to the carbocations 9 gave the final products 3 or 6.

  Scheme 4

  

  Scheme 4.  Proposed mechanistic pathway

  下载: 全尺寸图片 幻灯片

  3.   Conclusions

  In conclusion, tin powder-promoted C—C coupling reaction between allyl bromide and benzylic alcohol was achieved. The tin powder-participated reaction types were extended beyond 1, 2-addition to C＝O or C＝N double bounds. The protocol provides an efficient way to access potentially bioactive 3, 3-disubstituted-2-oxindole derivatives in good yields, and further expands the application of tin-powder-promoted reactions in organic synthesis.

  4.   Experimental

  4.1   Materials and methods

  The solvents were distilled by standard methods. Reagents were obtained from commercial suppliers and used without further purification unless otherwise noted. Silica gel column chromatography was carried out using silica gel 60 (230~400 mesh). Analytical thin layer chromatography (TLC) was done using silica gel GF254. TLC plates were analyzed by an exposure to ultraviolet (UV) light and/or submersion in phosphomolybdic acid solution or submersion in KMnO₄ solution or in I₂. High-resolution mass spectra were recorded on a Fourier transform ion cyclotron resonance mass spectrometer. NMR experiments were carried out in CDCl₃ and (CD₃)₂CO. ¹H NMR and ¹³C NMR spectra were recorded at 400 or 600 MHz and 100 or 150 MHz spectrometers, respectively. ¹⁹F NMR spectra were recorded at 376 MHz spectrometers. Chemical shifts are reported as δ values relative to internal TMS (δ 0.00 for ¹H NMR), chloroform (δ 7.26 for ¹H NMR), acetone (δ 2.05 for ¹H NMR), chloroform (δ 77.16 for ¹³C NMR), acetone (δ 206.26 for ¹³C NMR) and CFCl₃ (δ 0.00 for ¹⁹F NMR). Melting points were uncorrected.

  4.2   General procedure for the synthesis of 3, 6 and 8

  A mixture of tin powder (1.35 mmol, 4.5 equiv.) and allyl bromide (1.2 mmol, 4.0 equiv.) in THF was refluxed for 5 h, and then the solvent was evaporated off under vacuum to give a white solid residue, which was re-dissolved in 4 mL of DCM. 3-Hydroxy-2-oxindoles 1 or 5 (0.3 mmol, 1 equiv.) and HClO₄ (0.3 mmol, 1 equiv.) were added to the mixture. After stirring the mixture at room temperature for another 8~18 h, the saturated NaHCO₃ solution (5 mL) was poured into the mixture and stirred for 10 min. The mixture was extracted with EtOAc (10 mL×3). The combined organic phase was dried over MgSO₄ and then concentrated. Purification of the residue by silica gel column chromatography using petroleum ether/EtOAc (V/V＝3/1) as the eluent furnished the pure products 3, 6 and 8.

  3-Allyl-3-(4-methoxyphenyl)indolin-2-one (3a):^[9g] 73 mg, 87% yield, yellow solid. m.p. 92~94 ℃; ¹H NMR (400 MHz, CDCl₃) δ: 7.91 (s, 1H), 7.30~7.27 (m, 2H), 7.25~7.23 (m, 1H), 7.21 (d, J＝7.2 Hz, 1H), 7.08 (t, J＝7.2 Hz, 1H), 6.92 (d, J＝8.0 Hz, 1H), 6.84 (d, J＝8.8 Hz, 2H), 5.51~5.41 (m, 1H), 5.06 (d, J＝16.8 Hz, 1H), 4.95 (d, J＝10.4 Hz, 1H), 3.77 (s, 3H), 3.06~2.96 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.2, 159.0, 140.9, 132.6, 132.5, 131.5, 128.3, 128.2, 125.6, 122.6, 119.4, 114.1, 109.9, 56.3, 55.4, 42.0; HRMS (ESI) calcd for C₁₈H₁₇NNaO₂ [M+Na]⁺ 302.1157, found 302.1168.

  3-Allyl-3-(4-methoxyphenyl)-5-methylindolin-2-one (3b): 75 mg, 85% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.55 (s, 1H), 7.29 (d, J＝8.4 Hz, 2H), 7.03 (d, J＝7.8 Hz, 1H), 7.00 (s, 1H), 6.85 (d, J＝8.4 Hz, 2H), 6.81 (d, J＝7.8 Hz, 1H), 5.49~5.42 (m, 1H), 5.06 (d, J＝17.4 Hz, 1H), 4.94 (d, J＝9.6 Hz, 1H), 3.77 (s, 3H), 3.05~2.96 (m, 2H), 2.33 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.8, 158.8, 138.6, 132.9, 132.6, 132.0, 131.9, 128.6, 128.3, 126.0, 119.2, 114.1, 109.8, 56.5, 55.4, 41.7, 21.3; HRMS (ESI) calcd for C₁₉H₁₉NNaO₂ [M+Na]⁺ 316.1308, found 316.1310.

  3-Allyl-5-methoxy-3-(4-methoxyphenyl)indolin-2-one (3c): 76 mg, 82% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.00 (s, 1H), 7.30~7.27 (m, 2H), 6.86~6.83 (m, 2H), 6.83 (s, 1H), 6.80~6.77 (m, 2H), 5.50~5.43 (m, 1H), 5.07 (d, J＝17.4 Hz 1H), 4.96 (d, J＝10.2 Hz, 1H), 3.77 (s, 3H), 3.76 (s, 3H), 3.04~2.95 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.4, 159.0, 155.9, 134.4, 134.1, 132.5, 131.5, 128.3, 119.4, 114.1, 112.8, 112.6, 110.3, 56.8, 55.9, 55.4, 41.9; HRMS (ESI) calcd for C₁₉H₁₉NNaO₃ [M+Na]⁺ 332.1257, found 332.1255.

  3-Allyl-5-fluoro-3-(4-methoxyphenyl)indolin-2-one (3d): 67 mg, 75% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.47 (s, 1H), 7.27~7.24 (m, 2H), 6.96~6.92 (m, 2H), 6.86~6.83 (m, 3H), 5.48~5.41 (m, 1H), 5.05 (d, J＝17.4 Hz, 1H), 4.96 (d, J＝10.2, 1H), 3.77 (s, 3H), 3.02~2.94 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.6, 159.2 (d, J＝238.5 Hz), 159.1, 136.9 (d, J＝3.0 Hz), 134.4 (d, J＝7.5 Hz), 132.0, 130.9, 128.2, 119.8, 114.7 (d, J＝24.0 Hz), 114.3, 113.3 (d, J＝24.0 Hz), 110.6 (d, J＝9.0 Hz), 57.0, 55.4, 41.8; ¹⁹F NMR (376 MHz, CDCl₃) δ: －125.44 (m); HRMS (ESI) calcd for C₁₈H₁₆FNNaO₂ [M+Na]⁺ 320.1057, found 320.1062.

  3-Allyl-5-chloro-3-(4-methoxyphenyl)indolin-2-one (3e): 69 mg, 73% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.97 (br, 1H), 7.25~7.23 (m, 2H), 7.21~7.20 (m, 1H), 7.16 (d, J＝1.8 Hz, 1H), 6.86~6.84 (m, 3H), 5.48~5.41 (m, 1H), 5.06 (d, J＝17.4 Hz, 1H), 4.96 (d, J＝10.2 Hz, 1H), 3.77 (s, 3H), 3.03~2.95 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.7, 159.2, 139.7, 134.7, 131.9, 130.7, 128.3, 128.2, 128.0, 125.7, 119.9, 114.3, 111.2, 56.8, 55.4, 41.7; HRMS (ESI) calcd for C₁₈H₁₆ClNNaO₂ [M+Na]⁺ 336.0762, found 336.0763.

  3-Allyl-6-chloro-3-(4-methoxyphenyl)indolin-2-one (3f): 66 mg, 70% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.55 (s, 1H), 7.27~7.24 (m, 2H), 7.11 (d, J＝7.8 Hz, 1H), 7.05 (dd, J＝7.8, 1.8 Hz, 1H), 6.95 (d, J＝1.8 Hz 1H), 6.86~6.83 (m, 2H), 5.47~5.41 (m, 1H), 5.04 (d, J＝16.8 Hz, 1H), 4.96 (d, J＝10.2 Hz, 1H), 3.77 (s, 3H), 3.02~2.95 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.7, 159.1, 142.1, 133.9, 132.0, 131.0, 130.9, 128.2, 126.4, 122.6, 119.8, 114.2, 110.8, 56.1, 55.4, 41.8; HRMS (ESI) calcd for C₁₈H₁₆ClNNaO₂ [M+Na]⁺ 336.0762, found 336.0777.

  3-Allyl-7-chloro-3-(4-methoxyphenyl)indolin-2-one (3g): 64 mg, 68% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 7.84 (s, 1H), 7.29~7.27 (m, 2H), 7.25 (dd, J＝7.8, 0.6 Hz, 1H), 7.12 (d, J＝7.8 Hz, 1H), 7.04 (t, J＝7.8 Hz, 1H), 6.86~6.84 (m, 2H), 5.49~5.42 (m, 1H), 5.06 (d, J＝17.4 Hz, 1H), 4.98 (d, J＝10.2 Hz, 1H), 3.78 (s, 3H), 3.05~2.97 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 179.0, 159.2, 138.7, 133.9, 132.1, 130.8, 128.2, 128.1, 123.9, 123.4, 119.8, 115.2, 114.2, 57.5, 55.4, 42.1; HRMS (ESI) calcd for C₁₈H₁₆ClNNaO₂ [M+Na]⁺ 336.0762, found 336.0775.

  3-Allyl-5-bromo-3-(4-methoxyphenyl)indolin-2-one (3h): 83 mg, 78% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 9.06 (s, 1H), 7.36 (dd, J＝8.4, 1.8 Hz, 1H), 7.30 (d, J＝1.8 Hz, 1H), 7.26~7.24 (m, 2H), 6.87~6.85 (m, 2H), 6.81 (d, J＝8.4 Hz, 1H), 5.48~5.41 (m, 1H), 5.07 (d, J＝17.4 Hz, 1H), 4.97 (d, J＝10.2 Hz, 1H), 3.77(s, 3H), 3.03~2.95 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 179.7, 159.2, 140.0, 135.0, 132.0, 131.2, 130.6, 128.6, 128.2, 120.0, 115.3, 114.3, 111.4, 56.6, 55.4, 41.8; HRMS (ESI) calcd for C₁₈H₁₆BrNNaO₂ [M+Na]⁺ 380.0257, found 380.0260.

  3-Allyl-5-iodo-3-(4-methoxyphenyl)indolin-2-one (3i):85 mg, 69% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 9.28 (s, 1H), 7.54 (d, J＝8.4 Hz, 1H), 7.47 (s, 1H), 7.24 (d, J＝9.0 Hz, 2H), 6.87~6.85 (m, 2H), 6.72 (dd, J＝8.4, 1.8 Hz, 1H), 5.47~5.40 (m, 1H), 5.07 (d, J＝16.8 Hz, 1H), 4.97 (d, J＝10.2 Hz, 1H), 3.78 (s, 3H), 3.02~2.95 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.1, 159.0, 140.6, 137.0, 135.2, 133.9, 131.7, 130.6, 128.0, 119.8, 114.1, 112.1, 85.0, 56.4, 55.3, 41.5; HRMS (ESI) calcd for C₁₈H₁₆INNaO₂ [M+Na]⁺ 428.0118, found 428.0112.

  3-Allyl-3-(4-methoxyphenyl)-1-methylindolin-2-one (3j): 70 mg, 79% yield, yellow solid. m.p. 50~53 ℃; ¹H NMR (600 MHz, CDCl₃) δ: 7.34~7.31 (m, 1H), 7.31~7.28 (m, 2H), 7.25 (s, 1H), 7.11 (t, J＝7.8 Hz, 1H), 6.89 (d, J＝7.8 Hz, 1H), 6.84~6.81 (m, 2H), 5.43~5.36 (m, 1H), 5.02 (d, J＝16.8, Hz, 1H), 4.91 (d, J＝10.2 Hz, 1H), 3.77 (s, 3H), 3.19 (s, 3H), 2.99 (d, J＝7.2 Hz, 2H); ¹³C NMR (100 MHz, CDCl₃) δ: 178.4, 158.9, 144.0, 132.7, 131.9, 131.6, 128.3, 128.2, 125.3, 122.5, 119.2, 114.0, 108.3, 55.9, 55.4, 42.2, 26.5;

  3-Allyl-5-methoxy-3-(4-methoxyphenyl)-1-methylindolin-2-one (3k): 78 mg, 80% yield, white oil. ¹H NMR (600 MHz, CDCl₃) δ: 7.31~7.28 (m, 2H), 6.87~6.86 (m, 1H), 6.85~6.84 (m, 2H), 6.83~6.82 (m, 1H), 6.78 (d, J＝8.4 Hz, 1H), 5.44~5.37 (m, 1H), 5.06~5.02 (m, 1H), 4.94~4.92 (m, 1H), 3.80 (s, 3H), 3.76 (s, 3H), 3.17 (s, 3H), 2.99~2.97 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 178.0, 158.9, 156.0, 137.6, 133.3, 132.6, 131.6, 128.3, 119.2, 114.0, 112.7, 112.4, 108.5, 56.3, 55.9, 55.4, 42.1, 26.5; HRMS (ESI) calcd for C₂₀H₂₁NNaO₃ [M+Na]⁺ 346.1414, found 346.1401.

  3-Allyl-3-(4-methoxyphenyl)-1, 5-dimethylindolin-2-one(3l): 73 mg, 79% yield, white oil. ¹H NMR (600 MHz, CDCl₃) δ:7.31~7.29 (m, 2H), 7.12 (d, J＝7.8 Hz, 1H), 7.07 (s, 1H), 6.86~6.83 (m, 2H), 6.78 (d, J＝7.8 Hz, 1H), 5.44~5.37 (m, 1H), 5.04 (d, J＝17.4 Hz, 1H), 4.92 (d, J＝10.2 Hz, 1H), 3.77 (s, 3H), 3.18 (s, 3H), 3.03~2.96 (m, 2H), 2.37 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 178.3, 158.8, 141.6, 132.7, 132.1, 132.0, 131.9, 128.5, 128.3, 125.9, 119.0, 114.0, 108.0, 55.9, 55.3, 42.0, 26.4, 21.3; HRMS (ESI) calcd for C₂₀H₂₁NNaO₂ [M+Na]⁺ 330.1465, found 330.1454.

  3-Allyl-5-chloro-3-(4-methoxyphenyl)-1-methylindolin-2-one (3m):70 mg, 71% yield, white oil. ¹H NMR (600 MHz, CDCl₃) δ: 7.30~7.28 (m, 1H), 7.27~7.25 (m, 2H), 7.22 (d, J＝1.8 Hz, 1H), 6.85~6.83 (m, 2H), 6.80 (d, J＝8.4 Hz, 1H), 5.41~5.34 (m, 1H), 5.05~5.02 (m, 1H), 4.95~4.93 (m, 1H), 3.76 (s, 3H), 3.17 (s, 3H), 2.98~2.96 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 177.9, 159.1, 142.5, 133.8, 132.1, 130.9, 128.3, 128.1, 127.9, 125.5, 119.7, 114.2, 109.2, 56.1, 55.4, 42.0, 26.5; HRMS (ESI) calcd for C₁₉H₁₈ClNNaO₂ [M+Na]⁺ 350.0918, found 350.0909.

  3-Allyl-1-benzyl-3-(4-methoxyphenyl)indolin-2-one (3n):^[9g] 89 mg, 80% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 7.32~7.29 (m, 2H), 7.28~7.22 (m, 6H), 7.19 (t, J＝7.8 Hz, 1H), 7.07 (t, J＝7.2 Hz, 1H), 6.86~6.84 (m, 2H), 6.75 (d, J＝7.8 Hz, 1H), 5.46~5.39 (m, 1H), 5.08 (d, J＝16.8 Hz, 1H), 4.97~4.93 (m, 2H), 4.83 (d, J＝15.6 Hz, 1H), 3.78 (s, 3H), 3.11~3.02 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 178.5, 159.0, 143.1, 136.1, 132.7, 132.1, 131.9, 128.8, 128.3, 128.2, 127.7, 127.5, 125.3, 122.6, 119.4, 114.1, 109.4, 55.9, 55.4, 44.0, 42.2.

  1, 3-Diallyl-3-(4-methoxyphenyl)indolin-2-one (3o):^[9g] 69 mg, 71% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 7.31~7.29 (m, 2H), 7.28 (dd, J＝7.8, 1.2 Hz, 1H), 7.26~7.25 (m, 1H), 7.10 (td, J＝7.8, 1.2 Hz, 1H), 6.87 (d, J＝7.8 Hz, 1H), 6.85~6.82 (m, 2H), 5.82~5.76 (m, 1H), 5.44~5.37 (m, 1H), 5.20~5.18 (m, 1H), 5.17 (d, J＝1.8 Hz, 1H), 5.04 (dd, J＝16.8, 1.2 Hz, 1H), 4.92 (d, J＝10.2 Hz, 1H), 4.39~4.35 (m, 1H), 4.30~4.26 (m, 1H), 3.77 (s, 3H), 3.06~2.98 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 178.1, 158.9, 143.1, 132.6, 132.0, 131.8, 131.6, 128.3, 128.2, 125.3, 122.5, 119.4, 117.5, 114.1, 109.3, 55.8, 55.4, 42.5, 42.2.

  3-Allyl-1-butyl-3-(4-methoxyphenyl)indolin-2-one (3p): 79 mg, 79% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 7.32~7.27 (m, 3H), 7.24 (dd, J＝7.2, 0.6 Hz, 1H), 7.09 (td, J＝7.2, 0.6 Hz, 1H), 6.90 (d, J＝7.8 Hz, 1H), 6.85~6.82 (m, 2H), 5.42~5.35 (m, 1H), 5.03 (d, J＝16.8 Hz, 1H), 4.91 (d, J＝10.2 Hz, 1H), 3.77 (s, 3H), 3.75~3.70 (m, 1H), 3.67~3.62 (m, 1H) 3.04~2.96 (m, 2H), 1.66~1.60 (m, 2H), 1.39~1.32 (m, 2H), 0.93 (t, J＝7.8 Hz, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 178.2, 158.9, 143.5, 132.7, 132.3, 132.0, 128.2, 128.1, 125.3, 122.3, 119.2, 114.0, 108.6, 55.7, 55.4, 42.2, 40.0, 29.7, 20.3, 13.9; HRMS (ESI) calcd for C₂₂H₂₅NNaO₂ [M+Na]⁺ 358.1778, found 358.1794.

  3-(Allyloxy)-3-(4-methoxyphenyl)indolin-2-one (4a): 18 mg, 20% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.26 (s, 1H), 7.37~7.28 (m, 4H), 7.13~7.09 (m, 1H), 6.94 (d, J＝12.0 Hz, 1H), 6.87~6.82 (m, 2H), 5.99~5.89 (m, 1H), 5.31~5.26 (m, 1H), 5.15~5.13 (m, 1H), 3.99~3.95 (m, 1H), 5.85~5.81 (m, 1H), 3.77 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ:177.6, 159.9, 141.5, 134.3, 130.7, 130.2, 128.9, 127.9, 127.4, 126.3, 123.4, 117.1, 114.0, 110.6, 66.8, 55.4; HRMS (ESI) calcd for C₁₈H₁₇NNaO₃ [M+Na]⁺ 318.1106, found 318.1101.

  3-Allyl-3-(1H-indol-3-yl)indolin-2-one (6a):^[9g] 68 mg, 78% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 9.23 (br, 1H), 8.59 (br, 1H), 7.29 (d, J＝8.4 Hz, 1H), 7.20 (t, J＝7.8 Hz, 1H), 7.12~7.09 (m, 2H), 7.04 (d, J＝8.4 Hz, 1H), 6.99 (t, J＝7.2 Hz, 2H), 6.95~6.89 (m, 2H), 5.59~5.52 (m, 1H), 5.12 (d, J＝17.4 Hz, 1H), 4.98 (d, J＝10.2 Hz, 1H), 3.22~3.19 (m, 1H), 3.11~3.08 (m, 1H); ¹³C NMR (150 MHz, CDCl₃) δ: 181.6, 140.9, 136.9, 133.1, 132.2, 128.2, 125.6, 124.8, 123.4, 122.8, 122.2, 120.0, 119.7, 119.4, 114.4, 111.6, 110.1, 53.2, 40.8.

  3-Allyl-3-(5-methyl-1H-indol-3-yl)indolin-2-one (6b): 75 mg, 82% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.40 (s, 1H), 8.17 (s, 1H), 7.24 (t, J＝7.2 Hz, 1H), 7.20 (d, J＝8.4 Hz, 1H), 7.15 (d, J＝7.2 Hz, 1H), 7.04 (d, J＝2.4 Hz, 1H), 7.01 (t, J＝7.2 Hz, 1H), 6.95~6.93 (m, 2H), 6.91 (s, 1H), 5.58~5.51 (m, 1H), 5.10 (d, J＝17.4 Hz, 1H), 4.97 (d, J＝10.2 Hz, 1H), 3.22~3.18 (m, 1H), 3.11~3.08 (m, 1H), 2.28 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.8, 140.9, 135.3, 133.1, 132.4, 128.9, 128.2, 125.8, 125.0, 124.0, 123.3, 122.7, 120.0, 119.3, 114.4, 111.1, 109.8, 53.1, 40.9, 21.8; HRMS (ESI) calcd for C₂₀H₁₈N₂NaO [M+Na]⁺ 325.1317, found 325.1316.

  3-Allyl-3-(5-methoxy-1H-indol-3-yl)indolin-2-one (6c): 80 mg, 84% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.96 (s, 1H), 8.44 (s, 1H), 7.21 (t, J＝7.8 Hz, 1H), 7.17 (d, J＝8.4 Hz, 1H), 7.13 (d, J＝7.2 Hz, 1H), 7.06 (d, J＝2.4 Hz, 1H), 7.00 (t, J＝7.2 Hz, 1H), 6.90 (d, J＝7.8 Hz, 1H), 6.76 (dd, J＝8.4, 2.4 Hz, 1H), 6.37 (d, J＝1.8 Hz, 1H), 5.59~5.52 (m, 1H), 5.10 (d, J＝17.4 Hz, 1H), 4.97 (d, J＝10.2 Hz, 1H), 3.56 (s, 3H), 3.20~3.16 (m, 1H), 3.09~3.06 (m, 1H); ¹³C NMR (150 MHz, CDCl₃) δ: 181.2, 153.8, 141.1, 133.0, 132.2, 132.0, 128.3, 126.0, 125.1, 124.1, 122.8, 119.4, 114.1, 112.2, 112.1, 109.9, 102.1, 55.6, 53.1, 40.6; HRMS (ESI) calcd for C₂₀H₁₈N₂NaO₂ [M+Na]⁺ 341.1266, found 341.1261.

  3-Allyl-3-(5-bromo-1H-indol-3-yl)indolin-2-one (6d): 78 mg, 70% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.30 (s, 1H), 7.82 (s, 1H), 7.29 (t, J＝7.8 Hz, 1H), 7.24 (s, 1H), 7.19~7.18 (m, 1H), 7.17 (s, 1H), 7.16~7.14 (m, 1H), 7.11 (d, J＝2.4 Hz, 1H), 7.04 (t, J＝7.8 Hz, 1H), 6.98 (d, J＝7.8 Hz, 1H), 5.56~5.49 (m, 1H), 5.10 (d, J＝17.4 Hz, 1H), 4.99 (d, J＝10.2 Hz, 1H), 3.18~3.14 (m, 1H), 3.08~3.05 (m, 1H); ¹³C NMR (100 MHz, C₃D₆O) δ:178.7, 142.3, 136.2, 133.0, 128.3, 128.2, 127.6, 125.2, 124.9, 124.3, 122.8, 122.0, 118.5, 115.0, 113.5, 111.9, 109.7, 52.5, 40.7; HRMS (ESI) calcd for C₁₉H₁₅BrN₂NaO [M+Na]⁺ 389.0265., found 389.0263.

  3-Allyl-5-methyl-3-(5-methyl-1H-indol-3-yl)indolin-2-one (6e): 74 mg, 78% yield, red gel. ¹H NMR (600 MHz, CDCl₃) δ: 8.50 (s, 1H), 8.26 (s, 1H), 7.20 (d, J＝8.4 Hz, 1H), 7.04~7.02 (m, 2H), 6.94~6.93 (m, 2H), 6.90 (s, 1H), 6.83 (d, J＝7.8 Hz, 1H), 5.57~5.50 (m, 1H), 5.11 (d, J＝16.8 Hz, 1H), 4.97 (d, J＝10.2 Hz, 1H), 3.21~3.17 (m, 1H), 3.08~3.05 (m, 1H), 2.28 (s, 3H), 2.26 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.9, 138.4, 135.3, 133.2, 132.4, 132.1, 128.9, 128.5, 125.9, 125.6, 123.9, 123.2, 120.0, 119.2, 114.5, 111.1, 109.5, 53.1, 40.9, 21.8, 21.3; HRMS (ESI) calcd for C₂₁H₂₀N₂NaO [M+Na]⁺ 339.1468, found 339.1456.

  3-Allyl-3-(5-methoxy-1H-indol-3-yl)-5-methylindolin-2-one (6f): 81 mg, 81% yield, red gel. ¹H NMR (400 MHz, CDCl₃) δ: 8.67 (s, 1H), 8.41 (s, 1H), 7.19 (d, J＝9.2 Hz, 1H), 7.09 (d, J＝2.4 Hz, 1H), 7.03~7.00 (m, 1H), 6.94 (s, 1H), 6.82 (d, J＝8.0 Hz, 1H), 6.76 (dd, J＝8.8, 2.4 Hz, 1H), 6.36 (d, J＝2.4 Hz, 1H), 5.60~5.49 (m, 1H), 5.12 (d, J＝17.2 Hz, 1H), 4.98 (d, J＝10.0 Hz, 1H), 3.55 (s, 3H), 3.20~3.15 (m, 1H), 3.07~3.02 (m, 1H), 2.25 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.8, 153.9, 138.5, 133.0, 132.3, 132.2, 132.0, 128.6, 126.0, 125.8, 123.9, 119.3, 114.6, 112.3, 112.0, 109.4, 102.2, 55.6, 53.0, 40.7, 21.3; HRMS (ESI) calcd for C₂₁H₂₀N₂NaO₂ [M+Na]⁺ 355.1417, found 355.1410.

  3-Allyl-3-(5-chloro-1H-indol-3-yl)-5-methylindolin-2-one (6g): 70 mg, 69% yield, red gel. ¹H NMR (600 MHz, C₃D₆O) δ: 10.38 (s, 1H), 9.49 (s, 1H), 7.40 (s, 1H), 7.36 (d, J＝9.0 Hz, 1H), 7.24 (s, 1H), 7.07 (d, J＝7.8Hz, 1H), 7.02 (dd, J＝9.0, 2.4Hz, 1H), 7.00 (s, 1H), 6.92 (d, J＝7.8 Hz, 1H), 5.56~5.49 (m, 1H), 5.06 (d, J＝17.4 Hz, 1H), 4.92 (d, J＝10.2 Hz, 1H), 3.16~3.07 (m, 2H), 2.25 (s, 3H); ¹³C NMR (150 MHz, C₃D₆O) δ:179.5, 140.3, 136.3, 133.6, 133.5, 131.6, 129.0, 127.5, 125.8, 125.7, 124.7, 122.1, 120.1, 118.7, 115.8, 113.4, 109.8, 53.0, 41.1, 20.9; HRMS (ESI) calcd for C₂₀H₁₇ClN₂NaO [M+Na]⁺ 359.0922, found 359.0914.

  3-Allyl-3-(1H-indol-3-yl)-1, 5-dimethylindolin-2-one (6h): 70 mg, 73% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.69 (s, 1H), 7.30 (d, J＝8.4 Hz, 1H), 7.13 (d, J＝7.8 Hz, 1H), 7.09 (t, J＝7.8 Hz, 1H), 6.98 (s, 1H), 6.94 (d, J＝8.4 Hz, 1H), 6.91~6.88 (m, 2H), 6.85 (d, J＝7.8 Hz, 1H), 5.49~5.42 (m, 1H), 5.09 (d, J＝17.4 Hz, 1H), 4.95 (d, J＝10.2 Hz, 1H), 3.29 (s, 3H), 3.16~3.13 (m, 1H), 3.06~3.03 (m, 1H), 2.28 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 178.9, 141.5, 136.9, 132.6, 132.5, 132.3, 128.5, 125.6, 125.4, 123.3, 122.0, 120.1, 119.6, 119.1, 114.8, 111.5, 107.8, 52.7, 40.8, 26.5, 21.3; HRMS (ESI) calcd for C₂₁H₂₀N₂NaO [M+Na]⁺ 339.1468, found 339.1457.

  3-Allyl-1-benzyl-3-(1H-indol-3-yl)-5-methylindolin-2-one (6i):83 mg, 71% yield, yellow oil. ¹H NMR (400 MHz, CDCl₃) δ: 8.77 (s, 1H), 7.39~7.37 (m, 2H), 7.34~7.28 (m, 4H), 7.12~7.08 (m, 1H), 7.02 (d, J＝8.0 Hz, 1H), 6.98 (s, 1H), 6.95~6.94 (m, 1H), 6.86~6.85 (m, 2H), 6.75 (d, J＝8.0 Hz, 1H), 5.55~5.45 (m, 1H), 5.17 (d, J＝16.8 Hz, 1H), 5.07~4.93 (m, 3H), 3.28~3.22 (m, 1H), 3.12~3.07 (m, 1H), 2.24 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ:178.9, 140.6, 136.9, 136.2, 132.6, 132.5, 132.4, 128.9, 128.5, 127.8, 127.7, 125.6, 125.4, 123.4, 122.0, 120.3, 119.5, 119.3, 115.0, 111.5, 109.0, 52.8, 44.3, 41.0, 21.3; HRMS (ESI) calcd for C₂₇H₂₄N₂NaO [M+Na]⁺ 415.1781, found 415.1770.

  1, 3-Diallyl-3-(1H-indol-3-yl)-5-methylindolin-2-one (6j): 70 mg, 68% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.62 (s, 1H), 7.30 (d, J＝8.4 Hz, 1H), 7.11~7.08 (m, 2H), 7.00 (s, 1H), 6.98 (d, J＝7.8 Hz, 1H), 6.94 (d, J＝2.4 Hz, 1H), 6.90 (t, J＝7.2 Hz, 1H), 6.85 (d, J＝7.8 Hz, 1H), 5.90~5.83 (m, 1H), 5.52~5.45 (m, 1H), 5.31 (d, J＝17.4 Hz, 1H), 5.23 (d, J＝10.2 Hz, 1H), 5.11 (d, J＝16.8 Hz, 1H), 4.97 (d, J＝10.2 Hz, 1H), 4.50~4.47 (m, 1H), 4.36~4.32 (m, 1H), 3.21~3.17 (m, 1H), 3.07~3.04 (m, 1H), 2.28 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ:178.5, 140.7, 136.9, 132.6, 132.5, 132.3, 131.9, 128.4, 125.7, 125.4, 123.4, 122.0, 120.2, 119.6, 119.3, 117.8, 115.0, 111.6, 108.8, 52.7, 42.8, 41.0, 21.3; HRMS (ESI) calcd for C₂₃H₂₂N₂NaO [M+Na]⁺ 365.1624, found 365.1614.

  Ethyl 3-allyl-3-(1H-indol-3-yl)-5-methyl-2-oxoindoline-1-carboxylate (6k): 75 mg, 67% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.62 (s, 1H), 7.25~7.24 (m, 1H), 7.11~7.06 (m, 3H), 6.97 (s, 1H), 6.92~6.88 (m, 2H), 6.74 (d, J＝7.8 Hz, 1H), 5.56~5.49 (m, 1H), 5.08 (d, J＝16.8 Hz, 1H), 4.96 (d, J＝10.2 Hz, 1H), 4.55 (q, J＝17.4 Hz, 2H), 3.74 (s, 3H), 3.20~3.17 (m, 1H), 3.08~3.04 (m, 1H), 2.26 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 178.8, 168.4, 140.0, 136.9, 132.8, 132.4, 128.6, 125.6, 125.6, 123.4, 122.0, 120.3, 119.5, 119.1, 114.5, 111.5, 110.8, 107.8, 52.6, 52.6, 41.5, 41.1, 21.3; HRMS (ESI) calcd for C₂₃H₂₂N₂NaO₃ [M+Na]⁺ 397.1523, found 397.1512.

  3-Allyl-3-(p-tolyl)indolin-2-one (6l): 46 mg, 58% yield, yellow oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.68 (s, 1H), 7.25 (d, J＝2.4 Hz, 2H), 7.23 (d, J＝7.8 Hz, 1H), 7.19 (d, J＝7.2 Hz, 1H), 7.11 (d, J＝8.4 Hz, 2H), 7.06 (t, J＝7.8 Hz, 1H), 6.93 (d, J＝7.8 Hz, 1H), 5.49~5.42 (m, 1H), 5.05 (d, J＝17.4 Hz, 1H), 4.93 (d, J＝10.2 Hz, 1H), 3.06~3.00 (m, 2H), 2.30 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ:180.8, 141.1, 137.3, 136.6, 132.7, 132.5, 129.5, 128.2, 127.0, 125.4, 122.6, 119.4, 110.1, 56.8, 41.7, 21.1; HRMS (ESI) calcd for C₁₈H₁₇NNaO [M+Na]⁺ 286.1208, found 286.1205.

  3-Allyl-3-(3, 4-dimethoxyphenyl)indolin-2-one (6m): 79 mg, 85% yield, white oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.91 (s, 1H), 7.26~7.21 (m, 2H), 7.07 (t, J＝7.8 Hz, 1H), 6.97 (d, J＝1.8 Hz, 1H), 6.94 (d, J＝7.8 Hz, 1H), 6.89 (dd, J＝2.4 Hz, 1H), 6.79 (d, J＝8.4 Hz, 1H), 5.49~5.43 (m, 1H), 5.06 (d, J＝16.8 Hz, 1H), 4.94 (d, J＝10.2 Hz, 1H), 3.83 (s, 3H), 3.82 (s, 3H), 3.05~2.98 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.8, 149.0, 148.5, 141.1, 132.5, 131.9, 129.0, 128.3, 125.4, 122.5, 119.5, 119.4, 111.1, 110.7, 110.2, 56.6, 56.0, 55.9, 42.1; HRMS (ESI) calcd for C₁₉H₁₉NNaO₃ [M+Na]⁺ 332.1257, found 332.1254.

  3-Allyl-3-(3-methoxy-4-methylphenyl)indolin-2-one(6n):66 mg, 75% yield, white oil. ¹H NMR (600 MHz, CDCl₃) δ: 8.46 (s, 1H), 7.23 (t, J＝8.4 Hz, 2H), 7.09~7.04 (m, 2H), 6.93 (d, J＝7.8 Hz, 1H), 6.90 (d, J＝1.8 Hz, 1H) 6.84~6.82 (m, 1H), 5.51~5.44 (m, 1H), 5.08~5.05 (m, 1H), 4.96~4.94 (m, 1H), 3.77 (s, 3H), 3.07~3.00 (m, 2H), 2.17 (s, 3H); ¹³C NMR (150 MHz, CDCl₃) δ: 180.5, 157.9, 141.0, 138.2, 132.5, 132.4, 130.5, 128.1, 126.0, 125.3, 122.4, 119.2, 118.9, 110.1, 108.9, 57.0, 55.3, 41.8, 15.8; HRMS (ESI) calcd for C₁₉H₁₉NNaO₂ [M+Na]⁺ 316.1308, found 316.1301.

  3-Allyl-3-(3, 4-dimethylphenyl)indolin-2-one (6o): 54 mg, 65% yield, white oil. ¹H NMR (600 MHz, CDCl₃) δ: 9.00 (s, 1H), 7.07 (t, J＝7.8, 1.2 Hz, 1H), 7.19 (d, J＝6.6 Hz, 1H), 7.14 (s, 1H), 7.09~7.05 (m, 3H), 6.94 (d, J＝7.8 Hz, 1H), 5.51~5.44 (m, 1H), 5.08~5.05 (m, 1H), 4.95~4.93 (m, 1H), 3.09~3.01 (m, 2H); 2.23~2.22 (m, 6H); ¹³C NMR (150 MHz, CDCl₃) δ: 181.1, 141.2, 137.0, 136.9, 136.0, 132.9, 132.5, 130.0, 128.3, 128.1, 125.3, 124.5, 122.5, 119.3, 110.2, 56.8, 41.6, 20.1, 19.5; HRMS (ESI) calcd for C₁₉H₂₀NO [M+H]⁺ 278.1539, found 278.1532.

  But-3-ene-1, 1-diyldibenzene (8b):^[11] 30 mg, 48 % yield, yellow oil. ¹H NMR (400 MHz, CDCl₃) δ: 7.39~7.32 (m, 8H), 7.28~7.24 (m, 2H), 5.87~5.77 (m, 1H), 5.13 (d, J＝17.2 Hz, 1H), 5.05 (d, J＝10.4 Hz, 1H), 4.11 (t, J＝8.0 Hz, 1H), 2.94~2.90 (m, 2H); ¹³C NMR (150 MHz, CDCl₃) δ: 144.6, 137.0, 128.5, 128.1, 126.3, 116.4, 51.4, 40.1.

  Supporting Information Copies of ¹H NMR, ¹³C NMR, ¹⁹F NMR spectra and the HRMS data of compounds 3, 4a, 6 and 8b. The Supporting Information is available free of charge via the Internet at http://sioc-journal.cn/.

  
  
• 1. [1]

     (a) Roy, U. K.; Roy, S. Chem. Rev. 2010, 110, 2472.
     (b) Zha, Z.; Hui, A.; Zhou, Y.; Miao, Q.; Wang, Z.; Zhang, H. Org. Lett. 2005, 7, 1903.
     (c) Crich, D.; Grant, D.; Krishnamurthy, V.; Patel, M. Acc. Chem. Res. 2007, 40, 453.
     (d) Davies, A. G.; Gielen, M.; Pannell, K. H.; Tiekink, E. R. T. Tin chemistry: Fundamentals, Frontiers, and Applications; John Wiley & Sons, Chichester, U.K., 2008.

  2. [2]

     (a) Hoch, M. Appl. Geochem. 2001, 16, 719.
     (b) Amouroux, D.; Tessier, E.; Donard, O. F. X. Environ. Sci. Technol. 2000, 34, 988.
     (c) Lukevics, E.; Pudova, O. Biological Activity of Organotin and Organolead Compounds. In the Chemistry of Organic Germanium, Tin and Lead Compounds, Vol. 2, Ed.: Rappoport, Z., John Wiley and Sons, Chichester, 2002, p. 1685.
     (d) Barnes, J. M.; Stoner, H. B. Pharmacol. Rev. 1959, 11, 211.

  3. [3]

     (a) Solin, N.; Kjellgren, J.; Szabó, K. J. J. Am. Chem. Soc. 2004, 126, 7026.
     (b) Teo, Y.-C.; Goh, J.-D.; Loh, T.-P. Org. Lett. 2005, 7, 2743.
     (c) Suzuki, T.; Atsumi, J.-I.; Sengoku, T.; Takahashi, M.; Yoda, H. J. Organomet. Chem. 2010, 695, 128.
     (d) Deng, D.; Liu, P.; Ji, B.; Wang, L.; Fu, W. Tetrahedron Lett. 2010, 51, 5567.
     (e) Cormier, M.; Ahmad, M.; Maddaluno, J.; Paolis, M. D. Organometallics 2017, 36, 4920.
     (f) Mahajani, N. S.; Chisholm, J. D. Org. Biomol. Chem. 2018, 16, 4008.

  4. [4]

     Mukaiyama, T.; Harada, T. Chem. Lett. 1981, 10, 1527. doi: 10.1246/cl.1981.1527

  5. [5]

     (a) Elaas, N. A.; Elaas, W. A.; Huang, D.; Hu, Y.; Wang, K.-H. Curr. Org. Synth. 2017, 14, 1156.
     (b) Tan, K.-T.; Chng, S.-S.; Cheng, H.-S.; Loh, T.-P. J. Am. Chem. Soc. 2003, 125, 2958.
     (c) Alcaide, B.; Almendros, P.; Rodríguez-Acebes, R. J. Org. Chem. 2005, 70, 2713.
     (d) Appelt, H. R.; Limberger, J. B.; Weber, M.; Rodrigues, O. E. D.; Oliveira, J. S.; Lüdtke, D. S.; Braga, A. L. Tetrahedron Lett. 2008, 49, 4956.
     (e) Thorat, P. B.; Goswami, S. V.; Bhusare, S. R. Tetrahedron: Asymmetry 2013, 24, 1324.
     (f) Wang, Z.; Zha, Z.; Zhou, C. Org. Lett. 2002, 4, 1683.
     (g) Alcaide, B.; Almendros, P.; Aragoncillo, C.; Rodríguez-Acebes, R. J. Org. Chem. 2001, 66, 5208.
     (h) Estevam, I. H. S.; Bieber, L. W. Tetrahedron Lett. 2003, 44, 667

  6. [6]

     (a) Lin, M.-H.; Lin, L.-Z.; Chuang, T.-H.; Liu, H.-J. Tetrahedron 2012, 68, 2630.
     (b) Lin, M.-H.; Hung, S.-F.; Lin, L.-Z.; Tsai, W.-S.; Chuang, T.-H. Org. Lett. 2011, 13, 332.
     (c) Lin, M.-H.; Lin, W.-C.; Liu, H.-J.; Chuang, T.-H. J. Org. Chem. 2013, 78, 1278.

  7. [7]

     Liao, P.-H.; Bao, W.-L.; Zhang, Y.-M. Synth. Chem. 1997, 5, 374.

  8. [8]

     (a) Li, J.; Lv, W.; Huang, D.; Wang, K.-H.; Niu, T.; Su, Y.; Hu, Y. Appl. Organometal. Chem. 2014, 28, 286.
     (b) Xu, Y.; Huang, D.; Wang, K.-H.; Ma, J.; Su, Y.; Fu, Y.; Hu, Y. J. Org. Chem. 2015, 80, 12224.
     (c) Du, G.; Huang, D.; Wang, K.-H.; Chen, X.; Xu, Y.; Ma, J.; Su, Y.; Fu, Y.; Hu, Y. Org. Biomol. Chem. 2016, 14, 1492.
     (d) Wang, J.; Huang, D.; Wang, K.-H.; Peng, X.; Su, Y.; Hu, Y.; Fu, Y. Org. Biomol. Chem. 2016, 14, 9533.
     (e) Lu, A.; Huang, D.; Wang, K.-H.; Su, Y.; Ma, J.; Xu, Y.; Hu, Y. Synthesis 2016, 48, 293.
     (f) Ma, J.; Huang, D.; Wang, K.-H.; Xu, Y.; Chong, S.; Su, Y.; Fu, Y.; Hu, Y. Appl. Organometal. Chem. 2016, 30, 571.
     (g) Peng, X.; Wang, K.-H.; Huang, D.; Wang, J.; Wang, Y.; Su, Y.; Hu, Y.; Fu, Y. Appl. Organomet. Chem. 2017, 15, 6214.
     (h) Li, J.; Yang, T.; Zhang, H.; Huang, D.; Wang, K.-H.; Su, Y.; Hu, Y. Chin. J. Org. Chem. 2017, 37, 925(in Chinese).
     (李军, 杨天宇, 张怀远, 黄丹凤, 王克虎, 苏瀛鹏, 胡雨来, 有机化学, 2017, 37, 925.)
     (i) Li, J.; Huang, D.; Zhang, H.; Zhang, X.; Wang, J.; Wang, K.-H.; Su, Y.; Hu, Y. Chin. J. Org. Chem. 2017, 37, 2985(in Chinese).
     (李军, 黄丹凤, 张怀远, 张兴虎, 王娟娟, 王克虎, 苏瀛鹏, 胡雨来, 有机化学, 2017, 37, 2985.)
     (j) Yang, Z.; Huang, D.; Wen, L.; Wang, J.; Wang, K.; Hu, Y. Chin. J. Org. Chem. 2018, 38, 1725(in Chinese).
     (杨政, 黄丹凤, 文岚, 王娟娟, 王克虎, 胡雨来, 有机化学, 2018, 38, 1725.)
     (k) Liu, J.; Huang, D.; Wang, X.; Zong, W.; Su, Y.; Wang, K.; Hu, Y. Chin. J. Org. Chem. 2019, 39, 1767(in Chinese).
     (刘佳欣, 黄丹凤, 王小平, 宗吴中, 苏瀛鹏, 王克虎, 胡雨来, 有机化学, 2019, 39, 1767.)
     (l) Wang, X.; Huang, D.; Wang, K.-H.; Su, Y.; Hu, Y. J. Org. Chem. 2019, 84, 6946.
     (m) Wang, X.; Huang, D.; Wang, K-H.; Liu, J.; Zong, W.; Wang, J.; Su, Y.; Hu, Y. Appl. Organomet. Chem. 2019, 33, e4995.

  9. [9]

     (a) Naredla, R. R.; Klumpp, D. A. Chem. Rev. 2013, 113, 6905.
     (b) Nokami, T.; Yamane, Y.; Oshitani, S.; Kobayashi, J.-K, Matsui, S.-i.; Nishihara, T.; Uno, H.; Hayase, S.; Itoh, T. Org. Lett. 2015, 17, 3182.
     (c) Flagstad, T.; Petersen, M. T.; Nielsen, T. E. Angew. Chem., Int. Ed. 2015, 54, 8395.
     (d) Xiao, M.; Ren, D, Xu, L.; Li, S.-S.; Yu, L.; Xiao, J. Org. Lett. 2017, 19, 5724.
     (e) Hikawa, H.; Kotaki, F.; Kikkawa, S.; Azumaya, I. J. Org. Chem. 2019, 84, 1972.
     (f) Yu, H.; Lee, R.; Kim, H.; Lee, D. J. Org. Chem. 2019, 84, 3566.
     (g) Mayer, R. J.; Breugst, M.; Hampel, N.; Ofial, A. R.; Mayr, H. J. Org. Chem. 2019, 84, 8837.
     (h) Kinthada, L. K.; Medisetty, S. R.; Parida, A.; Babu, K. N.; Bisai, A. J. Org. Chem. 2017, 82, 8548.

  10. [10]

      Chan, T. H.; Yang, Y.; Li, C. J. J. Org. Chem. 1999, 64, 4452. doi: 10.1021/jo9901337

  11. [11]

      Lebleu, T.; Paquin, J-F. Tetrahedron Lett. 2017, 58, 442. doi: 10.1016/j.tetlet.2016.12.056

• 

  Scheme 1  Allylation reaction promoted by tin powder

  下载: 全尺寸图片 幻灯片
  

  Scheme 2  Allylation of tert-butyl 3-hydroxy-3-(4-methoxyphenyl)-2-oxoindoline-1-carboxylate

  下载: 全尺寸图片 幻灯片
  

  Scheme 3  Reaction of benzyl alcohols as substrate

  下载: 全尺寸图片 幻灯片
  

  Scheme 4  Proposed mechanistic pathway

  下载: 全尺寸图片 幻灯片

  表 1  Optimization of the reaction conditions^a

  Entry	Molar ratio of 1:2:Sn	Solvent	Acidb	Yieldc/%
  				3a	4a
  1	1.0:3.0:3.5	DCM	BiCl3	47	20
  2	1.0:3.0:3.5	DCM	FeCl3	0	0
  3	1.0:3.0:3.5	DCM	Fe(OTf)3	47	3
  4	1.0:3.0:3.5	DCM	InCl3	25	1
  5	1.0:3.0:3.5	DCM	In(OTf)3	33	2
  6	1.0:3.0:3.5	DCM	Ni(ClO4)2•6H2O	Trace	0
  7	1.0:3.0:3.5	DCM	NiCl2•6H2O	Trace	0
  8	1.0:3.0:3.5	DCM	Ni(OTf)2	6	1
  9	1.0:3.0:3.5	DCM	Mg(ClO4)2	19	0
  10	1.0:3.0:3.5	DCM	BF3•OEt2	5	Trace
  11	1.0:3.0:3.5	DCM	Sc(OTf)3	13	1
  12	1.0:3.0:3.5	DCM	Cu(OTf)2	47	4
  13	1.0:3.0:3.5	DCM	Yb(OTf)3	25	2
  14	1.0:3.0:3.5	DCM	TfOH	38	1
  15	1.0:3.0:3.5	DCM	H2SO4	40	2
  16	1.0:3.0:3.5	DCM	H3PO4	38	3
  17	1.0:3.0:3.5	DCM	HNO3	29	4
  18	1.0:3.0:3.5	DCM	HCl	35	3
  19	1.0:3.0:3.5	DCM	HClO4	46	1
  20	1.0:3.0:3.5	DCM	HClO4	58	0
  21	1.0:4.0:4.5	DCM	HClO4	87	0
  22	1.0:5.0:5.5	DCM	HClO4	82	0
  23	1.0:4.0:4.5	DCE	HClO4	65	0
  24	1.0:4.0:4.5	CH3CN	HClO4	54	3
  25	1.0:4.0:4.5	THF	HClO4	69	0
  26	1.0:4.0:4.5	1, 4-Dioxane	HClO4	85	0
  27	1.0:4.0:4.5	CH3OH	HClO4	Trace	0
  28	1.0:4.0:4.5	CH3CH2OH	HClO4	Trace	0
  a All reactions were carried out by using 0.3 mmol of 1a, 0.9~1.2 mmol of 2, 1.05~1.35 mmol of tin powder, 0.03~0.3 mmol of acid in 4 mL of solvent at room temperature for 10 h; bAcid: Entries 1~19, 10 mol%; Entries 20~28, 100 mol%; c Isolated yields.

  下载: 导出CSV

  表 2  Substrate scope of allylations using 3-hydroxy-2-oxindoles 1^a

  下载: 导出CSV

  表 3  Substrate scope of allylations using 3-hydroxy-2-oxindoles 5^a

  下载: 导出CSV
•