A novel and efficient one-pot synthesis of furo[3′,4′:5,6]pyrido[2,3-c]pyrazole derivatives using organocatalysts

A novel approach to one-pot synthesis of dihydrofuro[3',4':5,6]pyrido[2,3-c]pyrazole and indeno[2',1':5,6]pyrido[2,3-c]pyrazole derivatives have been investigated using organocatalysts that are recyclable. This new protocol has the advantages of environmental friendliness, higher yield, low cost, as well as convenient operation. The catalytic efficiency of various small organocatalysts such as L-proline, trans-4-hydroxy-L-proline, L-thiaproline, cinchonidine, (+)-cinchonine, and DL-2-phenylglycine has also been studied. (C) 2008 Elsevier Ltd. All rights reserved.