Triphenyl Thioborate

(PhS)3B

[1041-16-3]  · C18H15BS3  · Triphenyl Thioborate  · (MW 338.35)

(conversion of esters and a,b-unsaturated esters into phenylthio esters,1 and for formation of 1,3-bis(phenylthio)alkenes from aldehydes and ketones2)

Alternate Names: phenyl thioborate; tris(phenylthio)borane.

Physical Data: pale yellow solid; mp 140-143 °C;3 bp 196 °C/0.1 mmHg.3

Solubility: sol benzene, ether, acetone.4

Preparative Methods: can be made from Boron Triiodide and Diphenyl Disulfide;5 from Thiophenol and Boron Trichloride;6 from (phenylthio)borane trimer and thiophenol;7 or from Boron Trisulfide and thiophenol.2,8

Purification: recrystallize from benzene7 or distill in vacuo.3

Handling, Storage, and Precautions: sensitive to moisture and should be stored in a desiccator. Can be weighed out quickly in air, if humidity is low, but best handled in a dry box.2

Conversion of Esters and a,b-Unsaturated Esters into Phenylthio Esters.1

Esters are converted into phenylthio esters by heating with phenyl thioborate in refluxing xylene (140 °C) (eq 1), but the same transformation can be done at room temperature with phenyl thioaluminate. With the aluminum reagent, a,b-unsaturated esters give products contaminated with the b-(phenylthio) ester, but the boron reagent does not suffer from this disadvantage (eq 2).

Formation of 1,3-Bis(phenylthio)alkenes from Aldehydes and Ketones.2

a,b-Unsaturated aldehydes and ketones form 1,3-bis(phenylthio)alkenes on treatment with phenyl thioborate (eq 3). The (phenylthio)alkenes are b-acyl vinyl anion equivalents (eq 4).


1. Cohen, T.; Gapinski, R. E. TL 1978, 45, 4319.
2. Cohen, T.; Bennett, D. A.; Mura, A. J., Jr. JOC 1976, 41, 2506.
3. Finch, A.; Gardner, P. J.; Watts, G. B. Trans. Faraday Soc. 1967, 63, 1603.
4. Funk, H.; Koch, H. J. Wiss. Z. Martin-Luther Univ. 1959, 8, 1025 (CA 1961, 55, 11 417h).
5. Siebert, W.; Rittig, F. R.; Schmidt, M. JOM 1970, 22, 511.
6. Young, D. M.; Anderson, C. D. JOC 1961, 26, 5235.
7. Shchegoleva, T. A.; Lavrinovich, L. I.; Bochkareva, M. N.; Mikhailov, B. M. BAU 1968, 1780.
8. Brault, J.; Lalancette, J. M. CJC 1964, 42, 2903.

Philip L. Wickens & Derrick L. J. Clive

University of Alberta, Edmonton, Canada



Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.