Studies on the origin of cis-diastereo selectivity of the titanium-mediated cyclopropanation of carboxylic esters with Grignard reagents.: Stereochemistry of the intramolecular cyclization of β-metalloketones
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Kananovich, Dmitry G.
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Belarusian State Univ, Dept Organ Chem, Minsk 220030, BELARUSBelarusian State Univ, Dept Organ Chem, Minsk 220030, BELARUS
Kananovich, Dmitry G.
[1
]
Kulinkovich, Oleg G.
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Belarusian State Univ, Dept Organ Chem, Minsk 220030, BELARUSBelarusian State Univ, Dept Organ Chem, Minsk 220030, BELARUS
Kulinkovich, Oleg G.
[1
]
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[1] Belarusian State Univ, Dept Organ Chem, Minsk 220030, BELARUS
Data on the stereochemistry of the intramolecular cyclization of beta-metaloketones into 1,2-disubstituted cyclopropanols are in agreement with the cyclopropanation of carboxylic esters with alkoxytitanacyclopropane reagents proceeding via the beta-titanoketone inter-mediates with the metal atom bound to a secondary carbon. Hypothesis for the origin of cis-diastereoselectivity of the cyclization of the beta-titanoketones is suggested. It explains the tendency for the preferable formation of cis-1,2-disubstituted cyclopropanols by relief of repulsion strain between the ligands at the octahedral titanium atom. (c) 2007 Published by Elsevier Ltd.