Asymmetric metallation chromium tricarbonyl

Uemura demonstrated that enantiomerically pure (arylaldehyde)tricarbonyl-chromium complexes afford exclusively the //iraj-pinacols, providing an asymmetric synthesis of hydrobenzoins (Scheme 5.4).13 An intermediate involving coordination of the Sm(III) metal centre with the carbonyl oxygen was proposed to account for the high selectivity observed. This was supported by coupling experiments in the presence of HMPA, an additive that is known to prevent complexation, which led to the preferential formation of the erythro product. 

Catalytic asymmetric induction of planar chirality in an (arene)chromium complex has been reported in the cross-coupling of tricarbonyl (o-dichlorobenzene)chromium 30 with vinylic metals, where one of the meso chlorine atoms undergoes the coupling to give the monovinylation product 31 with up to 44% ee (Scheme 2-19) [38]. 

The asymmetric cross-coupling of the meso-tricarbonyl (ortho-dichloro-benzene)chromium complex with a wide range of vinylic metals in the... 

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