in 2-ethoxy-ethanol T=20°C; 3 h; Heating / reflux;

in acetonitrile inert atmosphere, Schlenk techniques; aq. Na(pic) soln. addn. to stirred mixt. of V-compd., NaO2CEt and MeCN, stirring overnight, NaCl ppt. filtration off, NEt4Cl addn. to filtrate, solvent removal (vac.), residue redissoln. (acetone), THF addn.; pptn. after a few on standing at room temp., ppt. filtration off, washing (THF), vac. drying; elem. anal.;

water; sodium hydroxide in ethanol T=95°C; 24 h;