is hydroxy the latter may be converted if desired to the corresponding compound of formula i in which r 6 is lower alkanoyloxy by conventional means for example by treatment with the appropriate lower alkanoic anhydride preferably in the presence of pyridine likewise it should be noted that similar use of the starting materials of formula ii in which x 39 is hydroxy and r 6 is benzyloxy to obtain the corresponding compound of formula i in which r 6 is hydroxy or lower alkanoyloxy is preferred for the preparation of the acid and ester compounds of this invention of formula i in which z is hydroxy or lower alkoxy and r 1 r 2 r 3 r 4 r 5 r 6 r 7 x and y are as defined in the first instance we have found that the following hitherto undisclosed process is both practical and convenient str10 in which r 1 r 2 r 3 r 4 r 5 r 6 r 7 x y and z are as defined in this instance x 39 is hydroxy or mercapto and r 16 is hydrogen or lower alkyl for convenience and clarity these particular acid and ester compounds of formula i are represented above as formula vii with reference to the above scheme the starting material of formula ii is condensed with a ketoacid vi r 16 h or a ketoester vi r 16 lower alkyl in the presence of.