[3520-15-8]  · C30H26Si2  · 1,4-Bis(diphenylhydrosilyl)benzene  · (MW 442.71)

(reducing reagent for esters under radical conditions)

Physical Data: mp 108 °C.

Solubility: sol benzene and THF.

Form Supplied in: white solid.

Preparative Methods: easily prepared by the Grignard reaction of Chlorodiphenylsilane with p-dibromobenzene (eq 1).

Handling, Storage, and Precautions: this reagent is stable in air. Because the toxicological properties are unknown, it should be handled in a well-ventilated hood.

1,4-Bis(diphenylhydrosilyl)benzene is a useful deoxygenating reagent for esters under radical conditions. Thus the reagent reacts with acetates in the presence of the radical generator 1,1-Di-t-butyl Peroxide (DTBP) at 140 °C to give the corresponding hydrocarbons (eq 2). Acetates derived from primary, secondary, and tertiary alcohols are reduced in high yield.1 Use of this reagent is preferred compared to monosilanes like Triphenylsilane,2 since the silicon-containing byproducts are higher boiling and more polar. Consequently, alkane products are easily isolated from reductions with this reagent.

This reduction can be applied to deoxygenation of carbohydrates. Both O-acetylfuranoses and pyranoses are converted to the corresponding deoxy sugars (Table 1).3 Acetylated derivatives of sugars which have an anomeric hydroxy group and vic-diols are also deoxygenated without any side reactions.4

1. Sano, H.; Takeda, T.; Migita, T. CL 1988, 119.
2. (a) Sano, H.; Ogata, M.; Migita, T. CL 1986, 77. (b) Sano, H.; Takeda, T.; Migita, T. S 1988, 402.
3. Sano, H.; Takeda, T.; Migita, T. to be published.
4. (a) Photodeoxygenation of the anomeric acetate gives free anomeric hydroxy compound: Pete, J.-P.; Portella, C.; Monneret, C.; Florent, J.-C.; Khuong-Huu, Q. S 1977, 774. (b) Deoxygenation of 1,2-diols via bis-xanthates using diphenylsilane gives alkenic compounds: Barton, D. H. R.; Jang, D. O.; Jaszberenyi, J. C. T 1993, 49, 7193.

Hiroshi Sano

Gunma University, Kiryu, Japan

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