Highly Enantioselective Regiodivergent Allylic Alkylations of MBH Carbonates with Phthalides

Phthalides were used for the first time in the allylic alkylation reactions with MBH carbonates for the creation of chiral 3,3-disubstituted phthalides. Highly enantioselective regiodivergent synthesis of gamma-selective or beta-selective allylic alkylation products was achieved by employing bifunctional chiral phosphines or multifunctional tertiary amine-thioureas as the catalyst, respectively. It was demonstrated that proper selection of catalysts and reaction conditions would differentiate an S(N)2'-S(N)2' pathway and an addition-elimination process, yielding different regioisomers of the allylic alkylation products in a highly enantiomerically pure form.