Hydrogenation of nitro compounds and imines

The selectivity of the hydrogenation halo-nitro aromatic compounds can be influenced by cyclodextrins, as additives, or by using cyclodextrin-derived catalysts [232] (see Ch. 10). 

It is clear from Table 3.9, that the effect is not related to the difference in electron density on the two phosphorus atoms since this should be the same with At =3 and N=l. Still the catalyst with trisulfonated BDPP gave 

Nevertheless, these studies nicely emphasized the warning of the authors of [146] ..large changes in enantioselectivity result from small energy differences (well below 5 kcal/mol) which can arise from apparently minor effects which are difficult to evaluate, such as solvation energies . Solvation 

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