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Chiral building blocks for the synthesis of nitrogen‐containing natural products, 5. The enantioselective synthesis of optically active, benzene nucleus‐substituted 1‐phenylethylamines from the corresponding acetophenones
Author(s) -
Bringmann Gerhard,
Geisler JoergPeter,
Geuder Torsten,
Künkel Georg,
Kinzinger Lioba
Publication year - 1990
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1990199001148
Subject(s) - chemistry , stereocenter , enantioselective synthesis , benzene , enantiomer , imine , optically active , ring (chemistry) , raney nickel , enantiomeric excess , organic chemistry , combinatorial chemistry , stereochemistry , catalysis
Abstract An efficient two‐step procedure for the synthesis of enantiomerically pure, benzene nucleus‐substituted 1‐phenylethylamines 1 is described, with predictable absolute configuration at the stereogenic center: Imine formation from the substituted acetophenones 6 with ( S )‐ or ( R )‐1‐phenylethylamine [( S )‐ 7 or ( R )‐ 7 ] and subsequent hydrogenation of the resulting Schiff bases 8 over Raney nickel leads to the secondary amines 9 and 10 in high diastereoselectivities. These dibenzylamines are cleaved regioselectively, usually next to the less substituted aromatic ring, giving the desired chiral 1‐phenylethylamines 1 in high yields and enantiomeric purities. Scope and limitations of this new and facile approach to the versatile building blocks 1 are reported.