Carbonyl compounds hydrogenation, stereochemistry

Additions of hydride donors to oc-chiral carbonyl compounds that bear only hydrocarbon groups or hydrogen at C-oc typically take place with the diastereoselectivities of Figure 10.14. One of the resulting diastereomers and the relative configuration of its stereocenters are referred to as the Cram product. The other diastereomer that results and its stereochemistry are referred to with the term anti-Cram product. 

The stereochemistry of the cathodic reaction of carbonyl compounds has been extensively studied from synthetic and mechanistic aspects. In this section the reaction is discussed in three parts hydrogenation to alcohols, hydrodimerization to pinacols, and cross-dimerization with unsaturated compounds. 

The stereochemistry at the a-carbon on hydrogenation of a,P-unsaturated carbonyl compounds in neutral solvents depends primarily on the nature of the... 

The diols, 33, 34, and 36, were oxidized with PCC to afford in good yield the ketones 38 - 40 respectively. The stereochemistries were determined by a detailed inspection of the NMR spectra of these compounds. The hydrogen at C-l, a to the carbonyl group in 38 and 39, will show the same coupling pattern if these are the trans fused compounds. However, if these are cis fused compounds they have different coupling patterns as they adopt different conformations due to... 

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