TY  - JOUR
A1  - Heller, Eberhard
A1  - Herdeis, Claus
T1  - Synthesis of 2S,5S- and 2R,5S-5-Hydroxypipecolic Acid via Amide-Methylenation of S-5-Hydroxy-2-piperidone with Dimethyltitanocene
N2  - A route to 2S,5S-and 2R,5S-hydroxypipecolic acid is presented, starting with the enantiopure 5S-5-hydroxy-piperidone 7. The key step of this reaction sequence is the chemoselsctive methylenation of the amide carbonyl group of 8 with dimethyltitanocene 9 to 10. The transformation of the exocyclic enecarbamate double bond to the carboxylic acid group is best accomplished via hydroboration/oxidation to the alcohol 11a,b. Separation and oxidation of the dlastereomers 11a,b, to 148. and 14b, and hydrolysis furnishes the diastereomeric pipecolic acids 15a and 15b in enantiopure form.
KW  - Chemie
KW  - Asymmetrie
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-38288
ER  -