Trienylboronic acid, a versatile coupling tool for retinoid synthesis; stereospecific synthesis of 13-aryl substituted (11Z)-retinal

Trienylboronic acid 1a was prepared from iodotriene 3, which was coupled with (2Z,4Z)-3-aryl-5-iodo-2,4-pentadienol 9 by Suzuki coupling reaction to give geometrically pure 13-aryl substituted (11Z)-retinol 10. Oxidation of 10 gave 13-aryl substituted (11Z)-retinal 11.