First stereoselective synthesis of diethyl cis- and trans-(4-hydroxy-1,2,3,4-tetrahydroquinolin-2-yl) phosphonates and ethyl phenylphosphinates from quinolin-4(1H)-one

We report here a practical method for the first stereoselective synthesis of novel diethyl cis- and trans-(4-hydroxy-1,2,3,4-tetrahydro-quinolin-2-yl)phosphonates, as well as the ethyl cis- and trans-(4-hydroxy-1,2,3,4-tetrahydroquinolin-2-yl)phenylphosphinates. The main feature of this method involves the regioselective 1,4-phosponylation to N-Cbz quinolin-4(1H)-one using diethyl phosphite or ethyl phenylphosphinate followed by the high diastereoselective reduction, to give the cis stereoisomers as favored products, which through the Mitsunobu reaction were converted into trans stereoisomers. Cleavage of N-Cbz bond under hydrogenolysis, gave the target heterocyclic α-aminophosphonates and α-aminophosphinates.