Organic Letters 2006-08-31

Formation and reactivity of silacyclopropenes derived from siloxyalkynes: stereoselective formation of 1,2,4-triols.

Timothy B Clark, K A Woerpel

Index: Org. Lett. 8(18) , 4109-12, (2006)

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Abstract

Silver phosphate-catalyzed silylene transfer to siloxyalkynes provided silacyclopropenes possessing a silyl enol ether functional group. Copper-catalyzed insertions of carbonyl compounds afforded the corresponding oxasilacyclopentenes. The embedded silyl enol ether functionality was treated with various aldehydes and a catalytic amount of Sc(OTf)3 to provide dioxasilacycloheptanones, which resulted from an aldol addition/rearrangement. Stereoselective reduction or allylation of the cyclic ketone, followed by n-Bu4NF deprotection, provided high yields of 1,2,4-triols possessing four contiguous stereocenters.