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Oxacycloalkenyliden‐Komplexe von Chrom, Molybdän und Wolfram: Synthese, Anellierung mit Alkinen und Diels‐Alder‐Reaktionen mit Dienen
Author(s) -
Christoffers Jens,
Dötz Karl Heinz
Publication year - 1995
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19951280212
Subject(s) - chemistry , cyclopentadiene , diels–alder reaction , cycloaddition , carbene , medicinal chemistry , diastereomer , chromium , acetal , methylene , annulation , ether , stereochemistry , fulvene , organic chemistry , catalysis
Reactions of Complex Ligands, LXI [1] . ‐ Oxacycloalkenylidene Complexes of Chromium, Molybdenum, and Tungsten: Synthesis, Their Annulation with Alkynes and Diels‐Alder Reaction with Dienes Lithiiated propargylic ether 1 reacts with M(CO) 6 (M = Cr, Mo, W) to give the 2‐oxacyclic carbene complexes 2–4 containing an α,β‐double bond and a cyclic acetal structure which serves as a protected benzoyl group. Reaction of the chromium complex 2 with tolan leads to an acyl hydroquinone derivative 5. The tungsten complex 3 undergoes a [4 + 2] cycloaddition with cyclopentadiene to give two diastereomeric oxatricyclic carbene complexes 6 and 7 with an endo/exo selectivity of 3:1. The stereochemistry of the Diels‐Alder reaction is controlled by the configuration of the acetal carbon center.