Synlett 2010(16): 2482-2484  
DOI: 10.1055/s-0030-1258055
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Base-Catalyzed Dehydrogenative Si-O Coupling of Dihydrosilanes: Silylene Protection of Diols

Agnieszka Grajewska, Martin Oestreich*
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstr. 40, 48149 Münster, Germany
Fax: +49(251)8336501; e-Mail: martin.oestreich@uni-muenster.de;
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Publikationsverlauf

Received 9 July 2010
Publikationsdatum:
19. August 2010 (online)

Abstract

The direct dehydrogenative coupling of 1,3- and 1,4-diols and dihydrosilanes is efficiently catalyzed by Cs2CO3 (10 mol%), cleanly affording six- and seven-membered 1,3-dioxo-2-silacycles with dihydrogen as the sole by-product. Conversely, 1,2-diols do not yield the expected 1,3-dioxo-2-silacyclopentanes, essentially forming cyclic disiloxanes instead. Aside from the synthetic convenience, the procedure itself is also useful for straight-forward diol derivatization prior to GLC analysis.

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General Procedure for Silylene Protection A flame-dried Schlenk flask was charged with Cs2CO3 (10 mol%). The flask was evacuated and backfilled with argon prior to the successive addition of the diol (1.0 equiv) dissolved in THF (0.15 M) and the dihydrosilane (1.2 equiv) dissolved in THF (0.50 M). The reaction mixture was maintained at r.t. for the indicated time, and the base was then filtered off. The filtrate was evaporated under reduced pressure, affording the crude silylene-protected diols, which were purified by flash column chromatography on silica gel.

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The reaction of Ph2SiH2 with H2O in the absence of base yields disiloxane (Ph2HSi)2O (cf. ref. 8).