Regio- and stereoselective synthesis of conjugated trienes from silaborated 1,3-enynes

Products obtained from palladium-catalyzed regioselective cis-addition of ( chlorodimethylsilyl)pinacolborane to the alkyne bond of 1,4-disubstituted 1,3-enynes were subjected to Suzuki-Miyaura coupling with alkenyl iodides. Hiyama coupling of the resulting silanol-functionalized trienes provided tetrasubstituted conjugated trienes with different substitution patterns, whereas protiodesilylation with fluoride gave trisubstituted trienes. The methodology presented gives access to conjugated trienes with control of regio- and stereochemistry.