Posts: 1 Re: Grubbs olefin metathesis Hi! I'm working on synthesis of assimetric imidazolium chlorides but I'm having problems in the last step. I'm following exactly the steps in the general procedure of Waltman and Grubbs (Organometallics, 23, 2004, 3105). I'm trying to synthesize the imidazolium salts combining mesityl with methyl and cyclohexyl group. The reduction of the oxalamides with BH3.THF is complete but in the last step I never get to close the ring with HC(EtO)3. After leaving the reaction mixture heating at 120 ºC and refluxing overnight, the next day I always find some very dark solution (almost black, like carbonized) and when I filtered the solid that appeared once in that solution I only could see in H-NMR and C-NMR that no peak of carbon at about 160 ppm was present (the one closing the ring, linked to two N). I also distilated EtOH formed during the reaction to force it to the right side and added more HCl to increase acidic conditions... Could someone help me, please?