ISSN:
1434-193X
Keywords:
Chirality
;
Catalysis
;
Amino acids
;
Crown ethers
;
Heterocyclic compounds
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
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 ZnEt2 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.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
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