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Cobalt( I )‐Mediated Intramolecular [2+2+2] Cocyclizations of (Methylenecyclopropyl)diynes as an Easy Access to Cyclopropanated Oligocycles
Author(s) -
Schelper Michael,
Buisine Olivier,
Kozhushkov Sergei,
Aubert Corinne,
de Meijere Armin,
Malacria Max
Publication year - 2005
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/ejoc.200500111
Subject(s) - chemistry , methylenecyclopropane , cyclopropane , diastereomer , intramolecular force , cyclopropanation , cobalt , stereochemistry , ring (chemistry) , diene , medicinal chemistry , catalysis , organic chemistry , natural rubber
Enediynes with methylenecyclopropane moieties attached either through the three‐membered ring or the double bond smoothly underwent cobalt‐mediated [2+2+2] cocyclizations to give cyclopropane‐fused and spirocyclopropanated cobalt‐complexed tricyclo[7.3.0.0 2,6 ]dodeca‐1,6‐dienes (1,2,3,3a,4,6,7,8‐octahydro‐ as ‐indacenes) under relatively mild conditions in yields ranging from 31 to 94 % (6 examples). Electron‐withdrawing substituents at the acetylenic terminus of the precursor are essential for a successful oligocyclization. While diphenyloxyphosphinyl‐substituted enediynes provided tricyclo[7.3.0.0 2,6 ]dodeca‐1,6‐diene complexes as mixtures of two diastereomers in high yields, the analogous methoxycarbonyl‐substituted precursors gave only one diastereomer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)