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New Chiral Catalysts Containing N,O ‐Heterocycles Derived from Chiral Amino Alcohols
Author(s) -
Juanes Olga,
RodriguezUbis Juan Carlos,
Brunet Ernesto,
Pennemann Helmut,
Kossenjans Michael,
Martens Jürgen
Publication year - 1999
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199912)1999:12<3323::aid-ejoc3323>3.0.co;2-w
Subject(s) - chemistry , catalysis , enantioselective synthesis , organic chemistry , chirality (physics) , organocatalysis , combinatorial chemistry , stereochemistry , chiral symmetry , physics , quantum mechanics , nambu–jona lasinio model , quark
The enantioselectivity exerted by a new series of chiral catalysts containing N , O ‐heterocycles of different sizes has been checked in the addition of diethylzinc to benzaldehyde, which was used as a model reaction. The catalysts were derived from natural amino acids, following a relatively simple procedure, and in several cases excellent ee values were obtained. The results were complementary since ee 's ranged from 98% ( R ) to 94% ( S ) excesses of the final 1‐phenylpropan‐1‐ol. Molecular mechanics calculations suggested that the production of the R alcohol may be explained by a mechanism similar to that described by Noyori, in which ZnEt 2 interacts solely with the N–C–C–OH fragment, whereas the formation of the S enantiomer needed the direct participation of the lateral chain of the parent amino acid and the N , O ‐heterocycle.