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Reagent‐controlled addition of ( R )‐ and ( S )‐2‐Hydroxy‐1,2,2‐triphenylethyl acetate to chiral aldehydes
Author(s) -
Mahler Ulrike,
Devant Ralf M.,
Braun Manfred
Publication year - 1988
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.19881211122
Subject(s) - chemistry , aldehyde , diastereomer , aldol reaction , reagent , enantiomeric excess , enantiomer , adduct , stereochemistry , deprotonation , ketone , medicinal chemistry , organic chemistry , enantioselective synthesis , catalysis , ion
The enantiomeric enolates ( R )‐ and ( S )‐ 2 , generated by double deprotonation of ( R )‐ and ( S )‐2‐hydroxy‐1,2,2‐triphenylethyl acetate ( 1 ) („HYTRA”), are added to chiral aldehydes 4 . It turnes out, that in this aldol reaction, the stereochemistry is largely determined by the configuration of the enolate 2 („reagent control”). Depending on the enantiomer of the reagent 1 , which is combined with one of the enantiomerically pure aldehydes 4 , either anti or syn adducts 11 and 12 are formed predominantly. The basic hydrolysis of the crude adducts 11/12 affords anti and syn carboxylic acids 5 and 6 in the corresponding diastereomeric ratios. By recrystallization of some of the mixtures 11/12 , the esters 11c, 11e , and 11g are available in high diastereomeric and enantiomeric purity. Scope and limitations of the method are discussed.