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Chiral Homoenolate Equivalents, V . Hydroxylakylation of Lithiated 3‐[( S )‐2‐(Methoxymethyl)pyrrolidino]‐1,3‐diphenylpropene – An Asymmetric Homoaldol Reaction
Author(s) -
Ahlbrecht Hubertus,
Kramer Andreas
Publication year - 1996
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.19961291004
Subject(s) - chemistry , allylic rearrangement , regioselectivity , adduct , solvent , medicinal chemistry , selectivity , stereochemistry , organic chemistry , catalysis
Abstract The hydroxyalkylation of lithiated 3‐[( S )‐2‐(methoxymethyl)‐pyrrolidino]‐1,3‐diphenylpropene ( 2 ) with aldehydes is completely regioselective giving homoaldol adducts in good yields. The simple diastereoselectivity is low with typical ratios ranging between 1:1 and 1:3 with the syn isomer predominating. The induced diastereoselectivity is much higher and is strongly solvent‐dependent. The reaction predominantly proceeds according to a metalloretentive mechanism from the si side of the allylic system in THF as well as in TBME. The induced diastereoselectivity obtained by the use of the less solvating TBME is considerably higher than in the strongly solvating THF, selectivities of up to 97% ee being reached.