Multi-component syntheses of 2-pyrrolines and organocatalytic asymmetric syntheses of functionalized chiral 2-pyrrolines

The green and atom-economical synthesis of functionalized 2-pyrrolines has been achieved by carrying out the multi-component tandem [2 + 2 + 1] annulation reaction of simple and commercially available starting materials, namely, an aldehyde, glycine ester hydrochloride, and benzoylacetonitrile. In the presence of a catalytic amount of bifunctional chiral squaramide, the sequential one-pot annulation reaction provided a highly stereoselective way to construct fully substituted 2-pyrrolines containing two contiguous stereocenters, from imino esters with benzoylacetonitriles in good yields under mild conditions.