Catalytic asymmetric 1,2-Addition/Lactonization tandem reactions for the syntheses of chiral 3-Substituted phthalides using organozinc reagents

Abstract

Using chiral phosphoramide ligand 2d-Zn (II) complex derived from (1R,2R)-1,2-diphenylethylenediamine as the catalyst, we have developed efficient catalytic asymmetric 1,2-addition/lactonization tandem reactions of diverse organozinc reagents with varied methyl 2-formylbenzoates for the construction of optically enriched 3-aryl or alkyl substituted phthalides, which are significant building blocks of many important chiral pharmaceuticals and natural products. The corresponding products could be afforded with good to excellent yields (up to 95%) and moderate to good enantioselectivities (up to 89%).