Rational design and organocatalytic enantioselective [1+4]-annulations of MBH carbonates with modified enones

According to the frontier molecular orbital theory, two types of modified enones have been designed and successfully applied in the chiral phosphine-catalyzed stereoselective [1 + 4]-annulation of Morita-Baylis-Hillman (MBH) carbonates for the first time. The reaction proceeds smoothly under mild conditions and exhibits excellent functional group tolerance, furnishing a broad scope of enantioenriched 2,3-dihydrofurans with high efficiency. DFT calculations have been applied to provide guidance for the design of additional enones and understand the origin of stereoselectivity. Importantly, this protocol further explores the scope of enones and enriches the chemistry of [1 + 4]-annulations of MBH carbonates for preparation of optically active multifunctional 2,3-dihydrofurans.