Organochromium(III) intermediates in reductive dimerizations and reductivemetatheses of organic substrates by novel chromium(I) reagents

The novel reductants of empirical formulas CrCl and CrH (or its Bu3Cr precu rsor) have been generated from CrCl3 and either 2 equiv of butyllithium in cold THF or 3 equiv of butyllithium in, hot toluene or THF, respectively. T he CrCl reagent in THF readily effects the reductive dimerization of variou s aldehydes, ketones, acyl halides, alpha-halo hetones, and a gamut of benz ylic halides, while CrH or its butylchromium(III) precursors in toluene bri ng about the reductive metathesis of polar bonds in carbonyl, epoxide, and nitro derivatives and with nickel catalysis, in vinylic or aryl halides.