Facile Diastereoselective Reactions of Chiral 1,3-Oxazolidines with Grignard Reagents; Asymmetric Syntheses of 2-Substituted and 2,6-Disubstituted Piperidines
Facile Diastereoselective Reactions of Chiral 1,3-Oxazolidines with Grignard Reagents; Asymmetric Syntheses of 2-Substituted and 2,6-Disubstituted Piperidines
Stereocontrolled preparation of cis- and rans-2,6-dialkylpiperidines via diastereoselective reaction of 1-aza-4-oxabicyclo[4.3.0]nonane derivatives with Grignard reagents
We report here the syntheses of cis- and trans-2,6-disubstituted piperidines using chiral 1-aza-4-oxabicyclo[4.3.0]nonane synthon 1, which shows high reactivity toward nucleophilic attack at its C-5 position. Bicyclic compounds resembling synthon 1 were transformed to cis- and trans-2,6-disubstituted piperidine derivatives via reactions with various Grignard reagents in a stereospecific manner. Using