Stereocontrolled synthesis of a prototype library of enantiopure 2,4-disubstituted 4-aryl-6-piperidinones and piperidines

Addition of a set of aryl cuprates to N-Boc O-TBDPS 2-hydroxymethyl 3,4-unsaturated 6-piperidinones affords syn-adducts in preference to anti when mixed Grignard-cuprates are used. Aryllithio cuprates give more of the anti-isomer in some cases. A library of 2-hydroxymethyl carbamates (27 compounds) and 2-hydroxymethyl aryl ethers and thioethers (19 compounds) was generated from a selection of 4-aryl-6-piperidinones, and some were further reduced to the corresponding piperidines (9 compounds).