Direct nucleophilic trifluoromethylation of carbonyl compounds by potent greenhouse gas, fluoroform: Improving the reactivity of anionoid trifluoromethyl species in glymes.

A simple protocol to overcome the problematic trifluoromethylation of carbonyl compounds by the potent greenhouse gas "HFC-23, fluoroform" with a potassium base is described. Simply the use of glymes as a solvent or an additive dramatically improves the yields of this transformation. Experimental results and DFT calculations suggest that the beneficial effect deals with glyme coordination to the K+ to produce [K(polyether)n]+ whose diminished Lewis acidity renders the reactive anionoid CF3 counterion species more 'naked', thereby slowing down its undesirable decomposition to CF2 and F- and simultaneously increasing its reactivity towards the organic substrate.