in tetrahydrofuran 2 h; mixture was poured on ice, extd. with ether, drying over Na2SO4, chromy. on SiO2 elution with benzene/pet. ether;

hydrogenchloride in methanol; benzene to soln. of the Sn-compound in a mixture of benzene and methanol added dropwise soln. of HCl in methanol (5 days); solvent evapd., recrystd. from petroleum ether at 30-40°C;