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Diastereoselective Generation of Quaternary Stereocenters by Ligand‐Controlled Palladium‐Catalyzed Allylations
Author(s) -
Meynhardt B.,
Lüning U.,
Wolff C.,
Näther C.
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(199909)1999:9<2327::aid-ejoc2327>3.0.co;2-h
Subject(s) - stereocenter , chemistry , palladium , stereoselectivity , ligand (biochemistry) , catalysis , stereochemistry , combinatorial chemistry , asymmetric induction , enantioselective synthesis , organic chemistry , receptor , biochemistry
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‐ E s 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.