Synlett 2009(6): 986-990  
DOI: 10.1055/s-0028-1088196
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of (Z)-1-Organylthiobut-1-en-3-ynes: Hydrothiolation of Symmetrical and Unsymmetrical Buta-1,3-diynes

Miguel J. Dabdoub*a, Vânia B. Dabdouba, Eder J. Lenardãob, Gabriela R. Hurtadoc, Sandro L. Barbosac, Jr., Palimécio G. Guerrerod, Carlos E. D. Nazárioe, Luiz H. Vianae, Amanda S. Santanaf, Adriano C. M. Baroni*f
a LASCO-Laboratório de Síntese de Compostos Organocalcogênios - Departamento de Química, FFCLRP, Universidade de São Paulo, Av. Bandeirantes, 3900 Ribeirão Preto, SP, Brazil
e-Mail: migjodab@usp.br;
b LASOL-Lab, Síntese Orgânica Limpa, Universidade Federal de Pelotas, PO Box 354, 96010-900 Pelotas, RS, Brazil
c Departamento de Farmácia-Bioquímica, Universidade Federal do Vale do Jequitinhonha e Mucuri, Diamantina, MG, Brazil
d Departamento de Química e Biologia, Universidade Tecnológica Federal do Parana, UTFPR, Curitiba, PR, Brazil
e Departamento de Química, Universidade Federal do Mato Grosso do Sul, Campo Grande, MS, Brazil
f Departamento de Farmácia-Bioquímica, Universidade Federal do Mato Grosso do Sul, Campo Grande, MS, Brazil
Fax: +55(67)33457365; e-Mail: adriano@nin.ufms.br;
Further Information

Publication History

Received 21 August 2008
Publication Date:
16 March 2009 (online)

Abstract

Hydrothiolation of 1-organylbuta-1,3-diynes and 1,4-diorganylbuta-1,3-diynes with the sodium organylthiolate anions, which were generated in situ by reacting diphenyl and dibutyl di­sulfide with NaBH4 in ethanol, results in the regio-, stereo-, and chemoselective formation of (Z)-1-organylthio-4-organylbut-1-en-3-ynes and (Z)-1-organylthio-1,4-diorganylbut-1-en-3-ynes, respectively.

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Typical Procedure for the Synthesis of ( Z )-1-Phenylthio-1,4-diorganylbut-1-en-3-ynes To a solution of 1,4-diphenylbuta-1,3-diyne 1a ¹7 (1.797 g, 5 mmol) and PhSSPh (1.845 g, 2.5 mmol) in 95% EtOH (20 mL) under a nitrogen atmosphere, NaBH4 (0.57 g, 15 mmol) was added at r.t. and under vigorous stirring. Gas evolution was observed during addition. The reaction mixture was stirred under reflux for 3 h, allowed to reach r.t., diluted with EtOAc (3 × 20 mL), and washed with brine (3 × 30 mL) and H2O (3 × 30 mL). After drying the organic phase over anhyd MgSO4, the solvent was removed under reduced pressure and the residue purified by flash chromatography on SiO2 using hexane as mobile phase, to give pure (Z)-1-phenylthio-1,4-diphenylbut-1-en-3-yne (2a) as a white solid; mp 92-95 ˚C; yield 72%. GC-MS: m/z (%) = 312 [M+], 202, 149, 105, 77, 28 (100). IR (KBr): 3072 (m), 2195 (m), 1680 (m), 1580 (s), 1481 (vs), 1440 (vs), 1071 (m), 1024 (m), 750 (vs), 740 (s), 687 (s) cm. ¹H NMR (400 MHz, CDCl3): δ = 6.32 (s, 1 H), 7.03-7.7 (m, 15 H). ¹³C NMR (100 MHz, CDCl3): δ = 87.60, 98.36, 112.27, 123.34, 126.39, 127.49, 127.88, 127.93, 128.27, 128.35, 128.64, 128.75, 129.25, 129.51, 131.60, 138.38, 147.20.

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Typical Procedure for the Synthesis of ( Z )-1-Phenylthio-4-organylbut-1-en-3-ynes A solution of 1-phenylbuta-1,3-diyne (1c, 10 mmol) was obtained in situ by reaction of 2-hydroxy-2-methyl-6-phenylhexa-3,5-diyne (1e, 1.84 g, 10 mmol) with powered NaOH (25 mg) in dry xylene (11 mL) under reflux for 15 min.²² The temperature was then allowed to reach r.t., and 95% EtOH (70 mL) and PhSSPh (1.845 g, 5.0 mmol) were added. The reaction was run under an atmosphere of N2 and NaBH4 (0.57 g, 15 mmol) was added. The resulting reaction mixture was refluxed for 3 h, diluted with EtOAc (70 mL), and washed with brine (4 × 30 mL). After drying the organic phase over anhyd MgSO4, the solvent was removed under reduced pressure, and the residue purified by flash chromatography on SiO2 using hexane as mobile phase, to give the pure phenylthio enyne 2c as a yellow oil; yield 75%. GC-MS: m/z = 236 [M+], 202, 149, 126, 115, 77, 51, 28 (100). IR (neat): 689 (vs), 742 (s), 756 (s), 816 (m), 1480 (m), 1488 (m), 1553 (w), 1585 (w), 2205 (w), 3055 (w) cm. ¹H NMR (400 MHz, CDCl3): δ = 5.83 (d, J = 10 Hz, 1 H), 6.75 (d, J = 10 Hz, 1 H), 7.22-7.54 (m, 10 H). ¹³C NMR (100 MHz, CDCl3): δ = 85.62, 97.95, 106.36, 123.26, 127.45, 128.30, 129.18, 129.19, 129.23, 130.31, 130,33, 130.36, 130.39, 130.41, 131.45, 131.49, 134.73, 138.91.

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1-Butylthio-4-cyclohexenylbut-1-en-3-yne (2j) The same procedure for obtaining 2c was performed,²0 however, 6-cyclohexenyl-2-methylhexa-3,5-diyn-2-ol (1k) and BuSSBu were used as starting materials, affording the pure compound 2j as a yellow oil; yield 50%. ¹H NMR (300 MHz, CDCl3): δ = 0.74-1.72 (m, 11 H), 2.07 (m, 2 H), 2.15 (m, 2 H), 2.74 (t, J = 7.2 Hz, 2 H)), 5.56 (d, J = 9.6 Hz, 1 H), 6.11 (s, 1 H), 6.39 (d, J = 9.6 Hz, 1 H). ¹³C NMR (75 MHz, CDCl3): δ = 13.4, 21.4, 21.5, 22.2, 25.6, 29.1, 32.4, 33.3, 83.4, 99.1, 104.8, 120.8, 134.2, 138.7.