Raney nickel ketones, stereoselective

Chelation by boron is believed to account for the high stereoselectivity shown in a new route to cryr/iro-1,3-diols (up to 98 2 eyrthro threo) from /3-hydroxy-ketones (Scheme 28) by reduction of the dibutylborinic acids (63). A stereodifferentiating hydrogenation of 1,3-diketones catalysed by Raney-nickel modified with (12,1 )-tartaric acid-sodium bromide has been shown to give (12,12)-l,3-diols [equation (18)] in optically pure form after recrystallization, although the isolated yields are low in some cases. ... 

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