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Up to Seven‐Component Adducts by Unprecedented Multiple Alkyne and Carbonyl Insertions in the Metal–Carbon Bond of Chromium Alkoxy Alkynyl Carbene Complexes
Author(s) -
Barluenga José,
GarcíaGarcía Patricia,
FernándezRodríguez Manuel A.,
Rocaboy Christian,
Aguilar Enrique,
Andina Facundo,
Merino Isabel
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700776
Subject(s) - alkyne , carbene , chemistry , moiety , triple bond , alkoxy group , adduct , metal carbonyl , chromium , cyclopentadienyl complex , medicinal chemistry , ligand (biochemistry) , stereochemistry , metal , polymer chemistry , double bond , organic chemistry , alkyl , catalysis , biochemistry , receptor
Chromium alkoxy alkynyl Fischer carbene complexes react with symmetrical internal alkynes to form new and different organometallic species, which result from consecutive insertions of several alkyne units and carbonyl groups into the metal–carbon bond. The insertion sequence can be controlled and, by slight modification of the reaction conditions, it can be directed to the preparation of either seven‐ or five‐component adducts. Three molecules of alkyne, two carbonyl groups, the carbene ligand and the chromium metal moiety partake in the creation of seven new carbon–carbon bonds and two five‐membered carbocycles in the first case while four new carbon–carbon bonds, a σ CrC(sp 2 ) bond and a cyclopentadienyl moiety are built in the second case. Evidence that five‐component chromium complexes are intermediates in the formation of seven‐component adducts is provided; they are also able to insert a unit of a different internal alkyne which confers more diversity to the seven‐component adducts. The presence of the σ CrC(sp 2 ) bond has also been exploited to develop the synthesis of both cyclopentene‐fused and novel spiro‐cyclopentenones as well as symmetrical biscyclopentenones. Finally, the isolation of six‐component adducts, when tolane was employed as the initial alkyne, provides further support to the proposed mechanism.