A novel route to 1,3-dienyl-2-boronic esters providing simple syntheses of conjugated [E,E]-dienes and conjugated [E]-alkenones.

Abstract A highly stereo- and regioselective synthesis of [ E ]-2-(1′-[ E ]-alkenylsubstituted-1′-alkenyl)-l,3,2-dioxaborinanes has been achieved for the first time via the nucleophilic substitution of [ Z ]-(1-bromo-1- alkenyl)boronic esters with [ E ]-l-lithio-l-alkenes. These are novel boron intermediates, which are converted into conjugated [ E,E ]-dienes and conjugated [ E ]-alkenones in good yields and in excellent stereochemical purities.