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Synlett 2009(5): 823-827  
DOI: 10.1055/s-0028-1087944
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Tunable Condensations between Ninhydrin and Sulfonium Salts Catalyzed by SeO2 and Cs2CO3 Leading to Highly Functionalized Vinyl Alcohols or Vinyl Sulfides

Qiyun Shao, Wenbo Shi, Chunbao Li*
Department of Chemistry, College of Science, Tianjin University, Tianjin, 300072, P. R. of China
Fax: +86(22)27403475; e-Mail: lichunbao@tju.edu.cn;
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Publication History

Received 22 October 2008
Publication Date:
24 February 2009 (online)

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Abstract

Condensation reactions between ninhydrin and sulfonium salts catalyzed by SeO2 and Cs2CO3 afforded highly functionalized vinyl alcohols and vinyl sulfides. In the reaction of ninhydrin with dipropyl phenacylsulfonium bromide catalyzed by SeO2 at room temperature in MeCN, highly functionalized vinyl alcohols were formed in good yields and high selectivities. When dimethyl phenacylsulfonium iodide was used in place of dipropyl phenacylsulfonium bromide, vinyl sulfides were produced in moderate to good yields.

Key words

catalysis - condensation - ninhydrin - selenium - sulfur ylide

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Typical Procedure for Preparing Compound 3
A mixture of ninhydrin (1, 178 mg, 1.0 mmol), dipropyl phenacylsulfonium bromide (2c, 317 mg, 1.0 mmol), SeO2 (22 mg, 0.2 mmol), and Cs2CO3 (33 mg, 0.1 mmol) in MeCN (10 mL) was stirred for 7 h at r.t. After complete consumption of the starting materials (TLC), MeCN was removed in vacuum to give yellow solid. The residue was treated with aq H2SO4 (10%, 1 mL) followed by brine (10 mL), and extracted with CH2Cl2 (2 × 50 mL). The combined organic layers were dried over anhyd Na2SO4. The extracts were then concentrated under reduced pressure, and the residue was purified by column chromatography (eluent: PE-EtOAc) on SiO2 to give a 83% yield of 3a.
¹H NMR (500 MHz, CDCl3): δ = 8.07 (d, J = 7.4 Hz, 1 H), 7.98 (d, J = 7.5 Hz, 2 H), 7.91-7.84 (m, 3 H), 7.65 (t, J = 7.4 Hz, 1 H), 7.52 (t, J = 7.8 Hz, 2 H) ppm. ¹³C NMR (125 MHz, CDCl3): δ = 189.24, 186.09, 185.49, 142.78, 139.22, 138.95, 136.21, 136.20, 134.67, 132.37, 131.09, 129.48, 129.06, 124.03, 123.95 ppm. IR (KBr): ν = 1737, 1699, 1670, 1622, 1589, 1451, 1354, 1330, 1246, 1121, 1060, 810, 741, 688 cm-¹. ESI-MS: m/z (%) = 277.2 (100) [M+ - H]. Anal. Calcd for C17H10O4: C, 73.38; H, 3.62. Found: C, 73.33; H, 3.61.

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Typical Procedure for Preparing Compound 4 A mixture of ninhydrin (1, 178 mg, 1.0 mmol), dimethyl phenacylsulfonium iodide (2d, 308 mg, 1.0 mmol), SeO2 (11 mg, 0.1 mmol), and Cs2CO3 (33 mg, 0.1 mmol) in MeCN (10 mL) was stirred for 4 h at r.t. After complete consumption of starting materials (TLC), MeCN was removed in vacuum to give yellow solid. The residue was treated with brine (10 mL) and extracted with CH2Cl2 (2 × 50 mL). The combined organic layers were dried over anhyd Na2SO4. The extracts were then concentrated under reduced pressure, and the residue was purified by column chromatography (eluent: PE-EtOAc) on SiO2 to give a 77% yield of 4a.
¹H NMR (500 MHz, CDCl3): δ = 8.02 (d, J = 7.7 Hz, 2 H), 7.92 (d, J = 7.3 Hz, 1 H), 7.76-7.68 (m, 3 H), 7.64 (t, J = 7.2 Hz, 1 H), 7.51 (d, J = 7.6 Hz, 2 H), 2.28 (s, 3 H) ppm. ¹³C NMR (125 MHz, CDCl3): δ = 190.68, 189.56, 185.92, 165.82, 141.61, 139.97, 134.95, 134.91, 134.73, 129.27, 128.71, 124.25, 123.36, 122.80, 14.46 ppm. IR (KBr): ν = 1672, 1595, 1551, 1451, 1351, 1246, 1153, 1076, 1043, 836, 737, 690 cm-¹. ESI-MS: m/z (%) = 309.4 (100) [M+ + H]. Anal. Calcd for C18H12O3S: C, 70.11; H, 3.92. Found: C, 70.15; H, 3.98.