Diastereoselective Reduction of the Enone Intermediate of Travoprost

A scalable process for the diastereoselective reduction of the prochiral enone intermediate 1 has been developed with DEANB/(R)-methyl CBS as reducing agent, to obtain the key intermediate alcohol 15R-isomer 2, used in a process for the manufacture of Travoprost (3). Various advantages of this process against the DMSB reduction assisted by (R)-methyl CBS have been studied. Specific comparison has been made to highlight the salient features of the chosen process on yield and optical purity with those of the DMSB reduction.