Enantio- and diastereoconvergent cyclocondensation reactions: synthesis of enantiopure cis-decahydroquinolines.

Up to four stereocenters with a well-defined configuration are generated in a single synthetic step by the cyclocondensation of (R)-phenylglycinol or (1S,2R)-1-amino-2-indanol with stereoisomeric mixtures (racemates, meso forms, diastereoisomers) of cyclohexanone-based δ-keto-acid and δ-keto-diacid derivatives in enantio- and diastereoconvergent processes that involve dynamic kinetic resolution and/or desymmetrization of enantiotopic groups. A detailed analysis of the stereochemical outcome of this process is presented. This method provides easy access to enantiopure 8- and 6,8-substituted cis-decahydroquinolines, including alkaloids of the myrioxazine family.