One pot four-component reaction for the efficient synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate derivatives

A novel one pot protocol has been developed to synthesize various spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate derivatives from the four-component reaction of isatin, malononitrile, hydrazine derivatives and dialkyl acetylenedicarboxylates. In this process two C-C bonds, two C-N bonds and one C-O bond have formed in one pot. The notable features of this protocol are simple and environmentally benign reaction condition, easy isolation of products, applicable to a wide range of readily available starting materials and good yields.