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Internal Lewis Acid Coordination as a Powerful Tool To Promote Highly Stereoselective Alkylation of α ‐Alkyl‐ β ‐Hydroxy Ketones with Grignard Reagents
Author(s) -
Bartoli Giuseppe,
Bellucci M. Cristina,
Bosco Marcella,
Marcantoni Enrico,
Sambri Letizia
Publication year - 1998
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/(sici)1521-3765(19981102)4:11<2154::aid-chem2154>3.0.co;2-o
Subject(s) - chemistry , alkylation , stereoselectivity , alkyl , reagent , ketone , chelation , alkoxy group , lewis acids and bases , solvent , medicinal chemistry , organic chemistry , catalysis
An α ‐alkyl‐ β ‐hydroxy ketone (1) was converted into the corresponding titanium alcoholate derivative 2 , which is a rigid and conformationally stable chelate complex, even in the presence of a coordinating solvent such as THF. The reaction of this complex with Grignard reagents allows the addition of a wide variety of carbon frameworks to the carbonyl function with high efficiency and stereoselectivity to give compounds such as 3 . This methodology overcomes the failure observed in the alkylation of closely related systems ( β ‐alkoxy derivatives) which are not able to produce stable chelated complexes.