Diastereoselective and branched-aldehyde-selective tandem hydroformylation-hemiaminal formation:synthesis of functionalized piperidines and amino-alcohols

Starting from readily available allylglycine, a tandem hydroformylation–hemiaminal formation reaction has been developed for the synthesis of chiral functionalized piperidines, with very good diastereoselectivity and branched regioselectivity using Rh/(S,S,S)-BOBPHOS catalysts. Tandem hydroformylation–hemiacetal formation also proceeds with good diastereoselectivity (88:12), with the hemiacetal product being hydrogenated with retention of stereochemistry to give a chiral intermediate used in the synthesis of the new antibiotic nemonoxacin