Isocyclic Allylsilanes: An Efficient One-Pot Synthesis of Allylic Hydroxymethyl Methylenecycloalkane Building Blocks by a Controlled H-ene/Protodesilylation Sequence Using Two Different Lewis Acids

Abstract

An efficient one-pot synthesis of useful allylic hydroxymethyl methylenecycloalkane building blocks was achieved by a controlled H-ene / protodesilylation sequence using two different Lewis acids (Me₂AlCl / SnCl₄) and starting from readily available isocyclic allylsilanes.

Notes

The separation and the characterization of the intermediate ene-type products was carried out for 5a and 6a (Scheme 1 and experimental section).

Readily available in two steps: trapping of organo-copper generated enolates (LDA generated enolates for the synthesis of 1a and 3a) with diethyl-phosphorochloridate to give enol phosphates (Taylor, J. K. Synthesis 1985, 364) then N₁(acac)₂ catalysed cross- coup ling with trirnethylsilylmethylmagesium chloride (Danishefsky, S. J.; Mantlo, N. J. Am. Chem. Soc. 1988, 110: 8129)