ISSN:
1434-193X
Keywords:
Quaternary carbon atoms
;
Palladium
;
Homogeneous catalysis
;
Configuration determination
;
NOE
;
Taft parameter
;
Diastereoselectivity
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The 1,2-asymmetric induction in the formation of new quaternary centers by palladium-catalyzed allylation of substituted cyanoacetates 1a-c was controlled by using 2,9-disubstituted 1,10-phenanthrolines as ligands, giving the allylated products 3a-c with like/unlike diastereoselectivities up to 94:6. The increased selectivities were caused by a tight wrapping of the allyl unit in the intermediate complexes. Differences in stereoselectivity for varying substrates can be understood when modified Taft parameters, the homo-Es values, are considered. The like/unlike isomers were assigned by using a combination of molecular modeling, NOE measurements and analyses of chemical shifts. An X-ray analysis of the acid 14 confirmed the structural assignment.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
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