Asymmetric synthesis of α-substituted aldehydes by Pd-catalyzed asymmetric allylic alkylation-alkene isomerization-Claisen rearrangement

Enantiospecific aliphatic Claisen rearrangement was realized with generally high chirality transfer. The requisite substrates were synthesized via Pd-catalyzed asymmetric allylic alkylation ( AAA) from easily obtained starting materials. After protection, the resultant bisallyl ethers underwent olefin isomerization and in situ Claisen rearrangement ( ICR) to generate r- chiral aldehydes. Remarkable chemoselectivity in the olefin isomerization step was observed. An asymmetric synthesis of communiol A was accomplished applying this methodology.