in chloroform-d1 byproducts: PPh3; inert atmosphere; 40°C, 7h; then 50°C, 31 h; reaction reversed on PPh3 addn.; not isolated, reaction followed by NMR spectroscopy;

in chloroform-d1 inert atmosphere; 40°C, 35 h; then 50°C, 18 h; not isolated, reaction followed by (1)H-NMR spectroscopy (product ratio changing with time);