Synthesis of 2H-pyran-2-ones and fused pyran-2-ones as useful building blocks

Abstract

A one-pot synthesis of 3-benzoylamino derivatives of 5- to 8-membered cycloalka[b]pyran-2-ones 5 and 2H-pyran-2-ones 10, starting from the appropriate alkanones 1 and 8, respectively, N,N-dimethylformamide dimethyl acetal (DMFDMA) and hippuric acid in the presence of a large excess of acetic anhydride, is described. A comparison of conventional thermal activation with microwave activation is given in the case of synthesis of 5c. The benzoyl protective group on amino moiety of the fused pyran-2-ones 5 and derivatives 11 was successfully removed by gentle heating in sulfuric acid resulting in the formation of the corresponding 3-aminocycloalka[b]pyran-2-ones 7 and 3-amino-2H-pyran-2-ones 12 in high yield. ©ARKAT USA, Inc.