Diastereoconvergent synthesis of trans-5-hydroxy-6-substituted-2-piperidinones by addition-cyclization-deprotection process.

A diastereoselective one-pot approach to access trans-5-hydroxy-6-substituted-2-piperidinones by an addition-cyclization-deprotection process has been developed, in which the stereogenic center at the C-6 position was solely controlled by α-OTBS group. The utility of this transformation is demonstrated by the asymmetric synthesis of the enantiomer of (-)-CP-99,994.