ISSN:
0947-6539
Keywords:
amines
;
asymmetric synthesis
;
C-C coupling
;
chiral auxiliaries
;
imines
;
zinc
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Triorganozincates were added to aliphatic aldimines derived from (S)-1-phenylethylamine and (S-valine esters in the presence of boron trifluoride to give secondary amines with low diastereoselectivies. From mixed zincates, most alkyl groups (methyl, ethyl, 1-heptynyl, but not tert-butyl) could be transferred. No addition to benzaldimines was observed, but the imines prepared from 2-pyridinecarboxaldehyde did not require activation by BF3 and underwent selective group transfer from mixed zincates at - 78°C. Excellent diastereoselectivities were observed in the reactions of the 2-pyridine imine derived from ethyl (S)-valinate with mixed zincates, in which the methyl group was used as nontransferable ligand, allowing the transfer of alkyl and vinyl groups with excellent to complete selectivity. However, dimethyl(aryl)- and dimethyl-(1-heptynyl)zincates did not react. (S)-1-(2-Pyridyl)alkylamines were prepared with high optical purity by subsequent removal of the chiral auxiliary.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.19970030512
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