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Highly Functionalized Bicyclo[3.2.1]octane Derivatives from Readily Available 2′‐Alkoxytricyclo[3.2.1.0 2,7 ]octanes: Building Blocks for Terpenes, Part I
Author(s) -
de Meijere Armin,
Hadjiarapoglou Lazaros,
Noltemeyer Mathias,
Gutke HansJürgen,
Klein Iris,
Spitzner Dietrich
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199803)1998:3<441::aid-ejoc441>3.0.co;2-e
Subject(s) - bicyclic molecule , chemistry , electrophile , octane , yield (engineering) , deprotonation , electrophilic addition , organic chemistry , medicinal chemistry , terpene , combinatorial chemistry , stereochemistry , catalysis , ion , materials science , metallurgy
2′‐Alkoxytricyclo[3.2.1.0 2,7 ]octanes 4‐R are obtained in good to excellent yields from methyl 2‐chloro‐2‐cyclopropylideneacetate ( 3 ) and the dienolates derived from the 3‐alkoxycyclohex‐2‐enones 1‐R and 2‐R , by a cascade of two consecutive Michael additions and a γ‐elimination. Compounds 4‐R are transformed to the correspondingly substituted bicyclo[3.2.1]octanecarboxylates 5 by treatment with acid. 2′‐Methoxytricyclooctanes 4a−d‐Me are readily deprotonated to give chelation‐stabilized cyclopropyllithium derivatives 6‐Me , which react with electrophiles to yield the 7′‐substituted tricyclo[3.2.1.0 2,7 ]octanes 4f−i‐Me (61−66%). By acidic workup of such reaction mixtures, or subsequent treatment of the isolated products 4f−i‐Me with acid, efficient transformation to the correspondingly substituted bicyclo[3.2.1]octanecarboxylates 5 is observed.