A novel synthesis of (Z)-2-(l-trimethylgermyl-l-alkenyl)-1,3,2-dioxaborinanes and their conversion into carboxylic acids

摘要

A novel procedure for preparing heterocyclic compounds such as (Z)-2-(l-trimethylgermyl-l-alkenyl)-l,3,2-dioxaborin-anes based on 1-trimethylgermyl-l-alkynes is described.1-Trimethylgermyl-l-alkynes easily obtainable by deprotonation of 1-alky-nes with n-butyllithium followed by treatment with trimethylgermanium chloride,are readily hydroborated in n-pentane in the presence of boron trichloride in hexane at 0 deg C for 3 h.The resulting supernatant clear solution was separated from boron trichloride-methyl sulfide complex.It was then reacted with 1,3-propane diol at 0 deg C for 0.5 h.The resulting representative (Z)-2-(l-tri-methylgermyl-l-alkenyl)-l,3,2-dioxaborinanes were isolated in good yields (65-86%) and in high stereochemical purities (>98%) as evidenced by NMR spectral data.The carbon skeletons present in these intermediates were confirmed by alkaline hydrogen peroxide oxidation to the corresponding carboxylic acids.