Synthesis of Highly Substituted Nitropyrrolidines, Nitropyrrolizines and Nitropyrroles via Multicomponent-Multistep Sequences within a Flow Reactor

We expand upon recent results concerning dipolar cycloaddition reactions of unstabilized azomethine ylids with nitro alkenes to generate 3-nitropyrrolidines via a flow chemistry sequence.This new work describes the development of a three-component coupling reaction between glycine esters, aldehydes and nitro alkenes.In order to further demonstrate the utility of flow technology in concert with heterogeneous reagents and scavengers for complex reaction sequences an in-line oxidation resulting in the conversion of tetra-substituted pyrrolidines to their pyrrole congeners has been developed.‡This paper is dedicated to Prof. Albert Eschenmoser on the occasion of his 85 th birthday and in acknowledgement of his many outstanding contributions to chemistry.