Synlett 2016; 27(03): 432-436
DOI: 10.1055/s-0035-1560587
letter
© Georg Thieme Verlag Stuttgart · New York

Bisallylation of Zirconacyclopentenes and Ring-Closing Metathesis: A Route to Eight-Membered-Ring Compounds

Nikola Topolovčan
Department of Organic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Praha 2, Czech Republic   eMail: martin.kotora@natur.cuni.cz
,
Illia Panov
Department of Organic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Praha 2, Czech Republic   eMail: martin.kotora@natur.cuni.cz
,
Martin Kotora*
Department of Organic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Praha 2, Czech Republic   eMail: martin.kotora@natur.cuni.cz
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Publikationsverlauf

Received: 16. September 2015

Accepted after revision: 04. Oktober 2015

Publikationsdatum:
09. November 2015 (online)


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Dedicated to Professor Ei-ichi Negishi on the occasion of his 80th birthday

Abstract

The cyclization of various enynes with the Negishi reagent provides the corresponding bicyclic zirconacyclopentenes, which after exposure to allyl chloride in the presence of a catalytic amount of copper(I) chloride, undergo bisallylation to furnish 1,9-decadienes in good yields (42–89%). The dienes are subjected to ring-closing metathesis to afford bicyclic compounds with [6.3.0]bicycloundecane (8,5-fused ring system) or [6.4.0]bicyclododecane (8,6-fused ring system) frameworks in good to excellent yields (52–92%). Selective monoallylation of a selected zirconacyclopentene followed by carboxyethylation with ethyl chloroformate gives rise to the corresponding ester, which after metalation and reaction with allyl bromide, furnishes a 1,9-decadiene. Ring-closing metathesis then yields the expected eight-membered cyclic product in 92% yield. This procedure constitutes a new pathway to bicyclic carbocyclic systems starting from 1,ω-enynes.

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