( R )‐1,2,2‐Triphenyl‐2‐(trimethylsiloxy)ethyl Propionate: anti‐Selective and Diastereofacially Selective Aldol Addition; Diastereoselective Silylation and Alkylation | Zendy

Sacha Hubert | Zendy; Waldmüller Delia | Zendy; Braun Manfred | Zendy

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( R )‐1,2,2‐Triphenyl‐2‐(trimethylsiloxy)ethyl Propionate: anti‐Selective and Diastereofacially Selective Aldol Addition; Diastereoselective Silylation and Alkylation

Author(s) -

Sacha Hubert,

Waldmüller Delia,

Braun Manfred

Publication year - 1994

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.19941271020

Subject(s) - chemistry , aldol reaction , ketene , alkylation , silylation , propionate , acetal , medicinal chemistry , deprotonation , diastereomer , benzaldehyde , propionates , stereoselectivity , adduct , aldol condensation , organic chemistry , aldehyde , stereochemistry , catalysis , ion

The propionates ( R )‐5 and ( R )‐ 6 which are derived from the readily available chiral auxiliary reagent ( R )‐triphenylglycol ( 4 ) have been applied in stereoselective aldol reactions. Whereas the enolate 7 and the silyl ketene acetal 12 , both generated from the ester ( R )‐ 6 , display only moderate diastereoselectivity when treated with benzaldehyde, ß‐hydroxyesters 8b and 16a , b are formed in diastereomeric ratios up to 95:5 (ratio of the main product to the sum of all other stereoisomers) when the propionate ( R )‐ 5 is subsequently deprotonated, transmetalated into the zirconium enolate and allowed to react with aldehydes. Alkaline hydrolysis or reduction with LiAlH 4 enables the conversion of the adducts 8a and 16a

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