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Synthesis of Polyfunctionalized Bicyclo[5.3.1]undecadiene Ring Systems Using a Two‐Carbon Ring‐Expansion of Cyclobutene Intermediates
Author(s) -
Mislin Gaëtan,
Miesch Michel
Publication year - 2001
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 - 10.1002/1099-0690(200105)2001:9<1753::aid-ejoc1753>3.0.co;2-e
Subject(s) - cyclobutene , chemistry , bicyclic molecule , cycloaddition , dimethyl acetylenedicarboxylate , ring (chemistry) , silyl enol ether , nonane , medicinal chemistry , electrophile , alicyclic compound , silylation , organic chemistry , stereochemistry , catalysis
The ZrCl 4 ‐catalyzed [2+2] cycloaddition of the silyl enol ether derived from monoprotected bicyclo[3.3.1]nonane‐2,6‐dione 7 with ethyl propynoate led after acidic treatment to the cyclobutene derivative 12 . Treatment of the latter with HBF 4 in refluxing ethanol smoothly afforded the two‐carbon ring‐expansion product 13 . On the other hand, the enolate of the β‐oxobicyclo[3.3.1]nonane ester 14 has been found to react with electrophilic acetylenes [ethyl propynoate, dimethyl acetylenedicarboxylate (DMAD)] to afford bicyclo[5.3.1]undecadiene derivatives 15 , 16 , most probably through the intermediacy of a tricyclo[5.3.1.0 2,5 ]undecene ring system.