in chloroform-d1 in an NMR tube, after 6 days at room temp., conversion was ca. 20 percent, further 5 days at 75 °C, conversion increased up to 35 percent; detected by NMR;

in chloroform-d1 in an NMR tube, 7 days at room temp. (50 percent conversion), after 24 h heating at 75 .degre.C the reaction was complete; detected by NMR;