in acetonitrile refluxing (4 h); further byproducts; filtration, addn. of ether, washing of org. layer (aq. NaCl), drying (over Na2SO4), crystn. (light petroleum);

in benzene refluxing (4 h); further byproducts; filtration, addn. of ether, washing of org. layer (aq. NaCl), drying (over Na2SO4), crystn. (light petroleum);