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Title:1-Aza-1'-Oxa(3,3)sigmatropic rearrangement: Synthesis of N-alkylindoles and 2,3-Dihydro-1h-Pyrrolo (1,2-A) Indole-9-Carboxylates
Author(s):Hutchins, Charles William
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Organic
Abstract:The {3,3}sigmatropic rearrangement of N-alkyl-N-aryl-O-acetoacetylhydroxylamines gives N-alkyl indoles in moderate yields under mild conditions. The substituted hydroxylamines were prepared by the condensation of aldehydes and ketones with an arylhydroxylamine and reduction of the nitrone so formed with sodium cyanoborohydride. This procedure affords high yields of N-alkyl-N-arylhydroxylamines and is tolerant of a wide variety of substituents.
O-Acetoacetylhydroxylamines formed by reaction with diketene, (beta)-keto esters, and (beta)-keto acids undergo rearrangement and dehydration to the N-alkylindoles.
A new synthetic method for the preparation of 2,3-dihydro-1H-pyrrolo{1,2-a}indole-9-carboxylates has been developed. The condensation of substituted N-arylhydroxylamines with ethyl 6-oxo-2-hexynoate in the presence of sodium cyanoborohydride afforded moderate yields of the pyrroloindoles over a five-step sequence of reactions. Sodium cyanoborohydride reduction of the nitrone condensation product, intramolecular conjugate addition of the hydroxylamine oxygen, and 1-aza-1'-oxa{3,3}sigmatropic rearrangement gives rise to a proposed benzazocinone intermediate. Transannular cyclization and dehydration then furnishes the pyrrolo-indolecarboxylates.
7-Methoxymitosene has been prepared from ethyl 2,3-dihydro-5-methoxy-6-methyl-1H-pyrrolo{1,2-a}indole-9-carboxylate by a short synthetic route which is adaptable for use in the synthesis of other analogues of the mitomycins.
Issue Date:1980
Description:201 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
Other Identifier(s):(UMI)AAI8026528
Date Available in IDEALS:2014-12-13
Date Deposited:1980

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