Synthesis of imidazo[5,1-b]thiazoles or spiro-β-lactams by reaction of imines with mesoionic compounds or ketenes generated from N-acyl-thiazolidine-2-carboxylic acids
作者:Giuseppe Cremonesi、Piero Dalla Croce、Concetta La Rosa
DOI:10.1016/j.tet.2003.10.093
日期:2004.1
New mesoionic compounds (2H, 3H-thiazolo[3,2-c]oxazol-7-ones) (beta) or ketenes ((3-acyl-1,3-thiazolidin-2-ylidene)methanone) (beta') were generated from N-acetyl and N-benzoyl-thiazolidine-2-carboxylic acids (7a,b) using different methods, and their reactivity towards N-(phenylmethylene)benzenesulfonamide (2) and N-(phenylmethylene)aniline (3) was tested. When (7a,b) were treated with (2) and acetic anhydride in refluxing toluene solution, only imidazo[5,1-b]thiazoles (8a,b) were obtained from the mesoionic compound intermediates (beta). When the ketene intermediates (beta') were generated from (7a,b) by means of Mukaiyama's reagent, only spiro-beta-lactams (9a,b) were isolated. (C) 2003 Elsevier Ltd. All rights reserved.