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Synlett 2004(12): 2159-2162  
DOI: 10.1055/s-2004-832806
LETTER
© Georg Thieme Verlag Stuttgart · New York

Thiopropenoylstannanes: The First Access to the Class of Thioacylstannanes

Alessandro Degl’Innocenti*, Antonella Capperucci*, Tiziano Nocentini, Simona Biondi, Valentina Fratini, Giulio Castagnoli, Irene Malesci
Dipartimento di Chimica Organica, ICCOM, Via della Lastruccia, 13 -50019 Sesto Fiorentino (FI), Italy
Fax: +39(055)4573585; e-Mail: alessandro.deglinnocenti@unifi.it;
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Publication History

Received 3 May 2004
Publication Date:
03 September 2004 (online)

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Abstract

Reaction of stannylated allenes with bis(trimethyl­silyl)sulfide/CoCl2·6H2O affords the first example of the synthesis of thioacylstannanes. The so obtained thiopropenoylstannanes behave as efficient thiabutadienes towards different in situ generated thioaldehydes and thioacylsilanes, leading to 2-substituted 4-stannyl-1,3-dithiacyclohex-4-ene derivatives through a regioselective hetero Diels-Alder reaction.

Key words

thioacylstannanes - thioacylsilanes - cycloadditions - heterodynes - dithiins

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Typical Procedure: A solution of 50 mg (0.17 mmol) of allene 1a and 72 µL (0.34 mmol, 61 mg) of HMDST in 0.7 mL of THF was slowly added at -78 °C under inert atmosphere with a solution of CoCl2·6H2O (40 mg, 0.17 mmol) in 2 mL of THF. The mixture was kept at -78 °C for 4 h, the progress of the reaction monitored by TLC, then allowed to reach r.t. After dilution with Et2O and washing with H2O, the organic phase was dried over Na2SO4. Evaporation of the solvent and purification on TLC (hexanes-Et2O 40:1) afforded 25 mg of 4a (49%) together with 12% of 5a. Compound 4a: 1H NMR (200 MHz, CDCl3): δ = 0.23 (9 H, s), 1.59 (3 H, d, J = 7.0 Hz), 3.24 (1 H, dd, J = 6.2 Hz, J = 17.4 Hz), 3.58 (1 H, bdd, J = 3.1 Hz, J = 17.4 Hz), 4.25 (1 H, q, J = 7.0 Hz), 5.95 (1 H, dd, J = 3.1 Hz, J = 6.2 Hz) ppm. 13C NMR (50 MHz, CDCl3): δ = -2.3, 20.9, 29.7, 30.3, 122.2, 125.5 ppm. MS: m/z (%) = 296 (8) [M+], 281 (4), 221 (19), 165 (79), 135 (22), 71 (100). Compound 5a: 1H NMR (200 MHz, CDCl3): d = 1.49 (3 H, d, J = 7.2 Hz), 3.25 (1 H, ddd, J = 1.4 Hz, J = 5.8 Hz, J = 18.0 Hz), 3.51 (1 H, ddd, J = 2.2 Hz, J = 3.4 Hz, J = 18.0 Hz), 4.20 (1 H, q, J = 7.2 Hz), 5.89 (1 H, ddd, J = 3.4 Hz, J = 5.8 Hz, J = 10.6 Hz), 6.21 (1 H, ddd, J = 1.4 Hz, J = 2.2 Hz, J = 10.6 Hz) ppm. 13C NMR (50 MHz, CDCl3): d = 21.9, 25.2, 40.6, 121.9, 137.0 ppm.

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General Procedure: To a solution of 50 mg (0.17 mmol) of allene 1a in 1.5 mL of THF were added, under N2 atmosphere, 151 mg (0.85 mmol) of benzoyltrimethylsilane 7b 18 and 426 µL (2.04 mmol, 363 mg) of HMDST. The mixture was cooled to -78 °C and added with a solution of 243 mg (1.02 mmol) of CoCl2·6H2O dissolved in 6.0 mL of THF. Progress of the reaction was monitored by TLC (hexanes-Et2O 40:1) and after 1.5 h at -78 °C the mixture was allowed to reach r.t. (ca. 15 °C), then diluted with Et2O and the organic phase washed with H2O and brine, and dried over Na2SO4. Evaporation of the solvent afforded the crude product. Purification on Florisil (hexanes-Et2O 40:1) afforded 23 mg of 9b (32%) and 8 mg of 1,2-dithiin isomer 11 (11%), together with minor amounts of the corresponding destannylated compounds (ca. 10%). Compound 9b: 1H NMR (200 MHz, CDCl3): d = 0.17 (9 H, s), 0.23 (9 H, s), 2.94 (1 H, dd, J = 6.2 Hz, J = 19.0 Hz), 3.08 (1 H, dd, J = 3.0 Hz, J = 19.0 Hz), 6.03 (1 H, dd, J = 3.0 Hz, J = 6.2 Hz), 6.96-7.90 (5 H, m) ppm. 13C NMR (50 MHz, CDCl3):
δ = -3.6, -2.7, 22.9, 47.2, 125.7, 127.5, 127.8, 128.3, 128.8, 141.5 ppm. MS: m/z (%) = 267 (6) [M+ - 163], 194 (8), 161 (11), 77 (19) 73 (100). Compound 11: 1H NMR (200 MHz, CDCl3): d = 0.03 (9 H, s), 0.10 (9 H, s), 2.50-2.30 (2 H, m), 5.92 (1 H, dd, J = 3.1 Hz, J = 6.0 Hz), 7.01-7.90 (5 H, m) ppm. 13C NMR (50 MHz, CDCl3): d = -3.7, -1.7, 40.1, 46.5, 125.5, 127.1, 128.0, 128.2, 128.5, 140.5 ppm. MS:
m/z (%) = 327 (21) [M+ - 103], 179 (13), 165 (10), 135 (32), 121 (28), 103 (27), 73 (100).