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Synthesis of Chiral Amino Alcohols Embodying the Bispidine Framework and Their Application as Ligands in Enantioselectively Catalyzed Additions to CO and CC Groups
Author(s) -
Spieler Jan,
Huttenloch Oliver,
Waldmann Herbert
Publication year - 2000
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(200002)2000:3<391::aid-ejoc391>3.0.co;2-r
Subject(s) - diethylzinc , chemistry , enantioselective synthesis , stereocenter , chalcone , alcohol , stereochemistry , catalysis , electrophile , steric effects , substituent , enantiomer , combinatorial chemistry , organic chemistry
Two generally applicable routes for the synthesis of chiral amino alcohols embodying the bispidine framework have been developed. In linear route A the bispidine framework is built up successively from chiral primary amines via intermediate formation of a piperidinone and a bispidinone. In convergent route B an achiral bispidine is formed first and then the N ‐substituents are introduced by reaction of the nitrogen bases with chiral electrophiles. In order to determine if the bispidine core and its N ‐substituents can influence the steric course of enantioselective transformations, bispidine amino alcohols built up by these two routes were investigated as chiral ligands in the enantioselectively catalyzed addition of diethylzinc to aldehydes and chalcone. In general, tridentate ligands containing one chiral amino alcohol fragment and a second amino substituent without a stereogenic center were more efficient than tetradentate ligands with two amino alcohol structural units. With the best ligands the enantioselective addition of diethylzinc to aromatic and aliphatic aldehydes proceeded with 83‐98% ee and the nickel‐catalyzed addition of diethylzinc to chalcone was achieved with up to 85% ee .