Eco-friendly reactions in PEG-400: a highly efficient and green approach for stereoselective access to multisubstituted 3,4-dihydro-2(1H)-quinazolines using 2-aminobenzylamines

摘要

An efficient and stereoselective synthesis of novel 3,4-dihydro-2(1H)-quinazolines has been developed through cyclization reactions of 2-aminobenzylamines with -oxoketene dithioacetals using PEG-400 as an inexpensive, easy to handle, non-toxic and recyclable reaction medium. The developed protocol is operationally simple and tolerates various substrates having different functionalities. This protocol features several attributes such as excellent yields, no work up, green reaction conditions, and being environmentally benign. The attractive feature of this new strategy is that all the reported final compounds have been isolated as single (E)-stereoisomeric forms, which was confirmed by (HNMR)-H-1 and X-ray crystallographic studies.