Stereocontrolled Synthesis of (11Z)-Retinal and Its Analogues

Abstract

Suzuki coupling of stereochemically pure (Z)-bromotetraene 1-which is extremely unstable but can be kept in frozen benzene in the presence of a small amount of PPh₃ at &sminus 01;20°C-and (Z)-alkenylboronic acid 2 provides the stereocontrolled synthesis of (11Z)-retinal 3. The 11Z configuration, which is introduced by selective catalytic debromination of the corresponding dibromo precursor of 1, is retained in this step. TBDMS = tBuMe₂ Si.