subsequently stirred for 2 hours at room temperature after addition of 5 ml of methanol the mixture was concentrated the residue after evaporation was column chromatographed on silica gel with n hexane with increasing addition of ether up to 100 after concentration of the eluate 0 9 g of oily n butyl carbamate were obtained that is 58 44 of the theoretical yield str25 empirical formula c 15 h 25 no 4 molecular weight 283 36 9 g of vii were dissolved in a mixture of 9 ml of pyridine and 9 ml of propionic anhydride and left to stand for 4 hours at room temperature after dilution with chloroform ice water was added to the mixture and acidification was effected with dilute hydrochloric acid followed by shaking after separation of the water phase the chloroform phase was washed once against water and once against dilute soda solution the water phases were individually extracted in each case 3 times with chloroform after concentration of the chloroform phases the residue after evaporation was column chromatographed on silica gel with n hexane with increasing addition of up to 50 of ether after evaporation of the eluate 4 2 g of oily xvii were obtained that is 36 of the theoretical yield str26 empirical formula c 13 h 20 o 4 molecular weight 240 30 1 g of ix was dissolved in 10 ml of dichloromethane 2 ml of isopropyl isocyanate and 220 mg of phenyl mercury acetate as catalyst were added and the mixture was subsequently left to stand for 10 hours at room temperature after addition of 5 ml of methanol the mixture was.