ABSTRACT
Polyhydroxylated pyrrolidines, such as biologically important azafuranoses represented by the natural product (+)-2,5-imino-2,5,6-trideoxy-gulo-heptitol and its C(3)-epimer, were elaborated from a commercially available enantiomerically pure (2R)-hydroxymethylaziridine by highly stereoselective directed reactions in more than 61% overall yield. At first, the nucleophile 2-trimethylsilyloxyfuran was directed to (2R)-aziridine-2-carboxaldehyde by ZnBr2 to yield the unusual anti-addition product as a single isomer via the chelation-controlled transition. The ring opening of aziridine was followed by conjugate addition to give a cis-fused bicycle, which was converted to the target molecule after the required reductive operations.
Subject(s)
Aza Compounds/chemical synthesis , Aziridines/chemistry , Biological Products/chemical synthesis , Pyrrolidines/chemical synthesis , Sugar Alcohols/chemical synthesis , Aza Compounds/chemistry , Biological Products/chemistry , Furans/chemistry , Models, Molecular , Pyrrolidines/chemistry , Stereoisomerism , Sugar Alcohols/chemistryABSTRACT
A new and efficient preparation of pharmacologically and biologically important 2,5-disubstituted 6-azaindoles was achieved from cyclizations of aziridin-2-yl dipropargylic alcohols as adducts of two propargyl groups to ethyl 1-benzylaziridine-2-carboxylate. The sequential cyclizations include pyrrole formation and a novel base-catalyzed intramolecular acetylenic Schmidt reaction.
