Triethylsilane—Benzoyl peroxide

The chemistry of )9-(thiocarbonyloxy)alkyl radicals stands in complete contrast to that of the (acyloxy)alkyl radicals, with elimination, while not the rule, being the norm [I]. The difference between the acyloxy and thiocarbonyloxy series is likely a consequence of the much weaker thiocarbonyl bond and the related higher stability of sulfur-centered radicals. The method has been developed in combination with the Barton deoxygenation method (Volume 1, Chapter 1.6) as a means of converting a vicinal diol, via the dixanthate, into an alkene (Scheme 33) [60-62]. Tributyltin hydride has been the reagent of choice for this reaction but it may also be conducted with the triethylsilane/benzoyl peroxide couple [63] and, doubtless, tris(trimethylsilyl)silane. 

Geminal polyhahdes also react with organosilanes under peroxide catalysis. For example, triethylsilane affords triethylchlorosilane in good yield upon reaction with carbon tetrachloride in the presence of benzoyl peroxide (bpo) at 80°C (94,100,102). 

Bromoform heated lOhrs. at 80° with 0.5 equivalent triethylsilane and a catalytic amount of benzoyl peroxide in a sealed tube methylene dibromide. Y ca. 100% based on startg. m. consumed. F. e., also with phenyldimethyl-silane, s. Y. Nagai, K. Yamazaki, and I. Shiojima, Bull. Ghem. Soc. Japan 2210 (1967) also partial dehydrohalogenation by addition of FeGlg s. E. T. Ghukovskaya, N. A. Kuz mina, and R. K. Freidlina, Dokl. Akad. Nauk SSSR 175, 1301 (1967) G. A. 68, 59024 with trichlorosilane/tri-n-butylamine s. R. A. Benkeser and W. E. Smith, Am. Soc. 90, 5307 (1968). 

---