Formation of N-substituted 4- and 7-oxo-4,5,6,7-tetrahydroindoles revisited: a mechanistic interpretation and conversion into 4- and 7-oxoindoles
作者:Antonio Garrido Montalban、Sven M. Baum、Justin Cowell、Alexander McKillop
DOI:10.1016/j.tetlet.2012.05.090
日期:2012.8
An efficient method for the preparation of 4-oxo-4,5,6,7-tetrahydroindoles was successfully applied to the synthesis of N-substituted 7-oxo-4,5,6,7-tetrahydroindoles for the first time. Both isomers where converted into their corresponding 4- and 7-oxoindoles in good yields utilizing a novel aromatization protocol. Based on the impurity profile obtained, however, different mechanisms for the formation of the 4- and 7-oxo-4,5,6,7-tetrahydroindole derivatives are discussed. In addition, the reaction sequences appear to be stereospecific allowing for the direct introduction of a chiral center a to the nitrogen and preparation of enantiomerically enriched products. (c) 2012 Elsevier Ltd. All rights reserved.