ALKALOID SYNTHESIS VIA THE INTRAMOLECULAR IMIDATE METHYLIDE 1,3-DIPOLAR CYCLO-ADDITION REACTION

A concise synthesis for the neurotoxic physostigmine alkaloid d,l-eserethole is described which relies upon an intramolecular cycloaddition reaction involving a "non-stabilized" imidate methylide and an unactivated alkene. The facility of this cyclization is enhanced by the rigid alignment...

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Bibliographic Details
Published inTetrahedron Vol. 41; no. 17; pp. 3559 - 3568
Main Authors SMITH, R, LIVINGHOUSE, T
Format Journal Article
LanguageEnglish
Published OXFORD Elsevier 01.01.1985
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
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Summary:A concise synthesis for the neurotoxic physostigmine alkaloid d,l-eserethole is described which relies upon an intramolecular cycloaddition reaction involving a "non-stabilized" imidate methylide and an unactivated alkene. The facility of this cyclization is enhanced by the rigid alignment inforced upon the dipole and dipolarophile by their ortho-disposition on an aryl nucleus. The synthetic limitations of this annulation method were revealed in an attempted synthesis of the erythrina skeleton. In this instance, prototropic rearrangement of the imidate methylide to the isomeric enamine occurred to the exclusion of the desired cyclization reaction.
ISSN:0040-4020
1464-5416
DOI:10.1016/S0040-4020(01)96709-2