An iminophosphorane-based approach for the synthesis of spiropyrrolidine–imidazole derivatives
作者:Pilar M. Fresneda、Marta Castañeda、Miguel Angel Sanz、Delia Bautista、Pedro Molina
DOI:10.1016/j.tet.2006.12.021
日期:2007.2
A method based on the reaction of an E-phosphazide, an intermediate in the Staudinger reaction between triphenylphosphine and an azide, with heterocumulenes allows the one-pot, two-component synthesis of a number of pyrrole-imidazole derivatives. The procedure, which involves sequential treatment of the appropriate a-azido ester with triphenylphosphine and isocyanate leads to the hydantoin product after aqueous work-up. The cyclization conditions can also be adapted for the synthesis of thiohydantoins by using isothiocyanates. These hybrids pyrrole-thiohydantoins undergo a novel oxidative spirocyclization by action of DDQ to give a tricyclic derivative (pyrrole-pyrrolidine-imidazole), which displays an interesting cytotoxic activity. (c) 2006 Elsevier Ltd. All rights reserved.