Synthesis of Substituted 5-(Pyrrolidin-2-yl)tetrazoles and Their Application in the Asymmetric Biginelli Reaction

A series of chiral substituted 5-(pyrrolidin-2-yl)tetrazoles have been synthesized and evaluated as organocatalysts for the asymmetric Biginelli reaction. The relationship between catalytic activity and the different catalyst structures is briefly discussed. By using the optimized catalyst C-10 (10 mol-%), a series of 3,4-dihydropyrimidin-2(1H)-one (DHPM) derivatives have been obtained in 63-88 % yields and 68-81 % ee values within 24 h at room temperature. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)