Grignard reagents add diastereo- and regioselectively to the γ-position of N-(2,3,4,6-tetra-O-pivaloyl-β-d-galactopyranosyl)-1,2-dihydro-pyridin-2-one in situ, when activated by trimethylsilyl trifluoromethanesulfonate yielding enantiomerically pure 4-substituted N-galactosyl-5,6-didehydro-2-piperidinones.
Stereoselective Synthesis of 3-Substituted and 3,4-Disubstituted Piperidine und Piperidin-2-one Derivatives
作者:Ellen Klegraf、Horst Kunz
DOI:10.1515/znb-2012-0413
日期:2012.4.1
The stereoselective synthesis of 3-substituted and 3,4-disubstituted piperidine and piperidin-2-one derivatives was achieved starting from 2-pyridone. After N-galactosylation and subsequent O-silylation, nucleophilic addition of organometallic reagents proceeded with high regio- and stereoselectivity at 4-position. Substituents at position 3 were stereoselectively introduced by reaction of electrophiles
Stereoselective desymmetrization of 4-pyridone has been achieved through selective N-galactosylation, activation of the N-(galactosyl)pyridone by O-silylation and immediate addition of Grignard compounds. Chiral piperidine derivatives, e.g. (S)-(+)-coniine and (5S,9S)-(+)-indolozidine 167B, were synthesised in enantiomericallypure form using these highly regio- and stereoselective reactions. After