Stereoselective Synthesis of 1,2,4-Triols from Silylenol Ethers

Significance

1,2,4-Triols with four contiguous stereocenters can be prepared in five steps (56-63% overall). A silacyclopropene was formed under Ag(I)-catalyzed silylene transfer conditions, and the high reactivity of the strained-ring silanes was harnessed in a selective CuI-catalyzed insertion of an aldehyde in the presence of a reactive cyclopropenylsilylenol ether. The addition on the vinylsilyl moiety to a second aldehyde utlilizes a Lewis acid for the reaction to occur, and is followed by a 1,3-Brook rearrangement. If the first aldehyde is replaced by a formate, an acetal intermediate 7 is obtained, which can be used for further diastereoselective C-C bond formation.