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By using the iridium complex of a phosphine-oxazoline ligand with an axis-unfixed biphenyl backbone, a highly enantioselective hydrogenation of the C=C bond of exocyclic a,b-unsaturated carbonyl compounds to afford a-chiral cyclic ketones, lactones and lactams was developed.Keywords: asymmetric synthesis; cyclic carbonyl compounds; hydrogenation; iridium; oxazoline Cyclic carbonyl compounds with a-chiral carbon centers are an important group of compounds in organic synthesis and medicinal chemistry.[1] For the synthesis of these optically active compounds, enzyme-mediated reactions and chemical syntheses from optically active starting materials have usually been used. [2,3] However, most of the reported methods are limited in substrate scope, and high enantioselectivity has seldom been obtained. The most straightforward and simplest approach to these compounds would be asymmetric hydrogenation of cyclic a,b-unsaturated carbonyl compounds but much less efforts have been focused on this option. [4,5] In most recent years, iridium complexes with chiral phosphine-oxazoline ligands have attracted much attention because of their easy availability and high reactivity and enantioselectivity in the hydrogenation of unfunctionalized olefins [6] or olefin substrates with less strongly coordinating groups [7][8][9][10] . In this context, Zhou found that the C=C bond of an a,b-unsaturated carboxylic acid could be hydrogenated with high enantioselectivity by using an iridium spirophosphine-oxazoline (SIPHOX) complex; [8] Bolm and Hou found that the C=C bond of a,b-unsaturated ketones can be hydrogenated with high enantioselectivity by using an iridium phosphineoxazoline (PHOX) complex; [9] Hou further investigated the enantioselective hydrogenation of a,b-unsaturated amides by using an iridium complex derived from ferrocenylphosphine-oxazoline (Fc-PHOX).[10]However, there are few examples focused on the establishment of a-chiral carbon centers of cyclic carbonyl compounds, especially for lactones and lactams, via asymmetric hydrogenation. [4,9] Even in these limited examples, the asymmetric hydrogenation is strongly substrate dependent and there is no general solution for different kinds of cyclic substrates. Herein, we disclose our preliminary results of the highly enantioselective hydrogenation of exocyclic a,b-unsaturated carbonyl compounds by using an iridium complex with axis-unfixed biphenylphosphine-oxazoline ligands 1 (Scheme 1).Scheme 1. Complexation behavior of ligands 1a-f.

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The emergence and spread of bacteria carrying the bla NDM-1 gene has become a worldwide concern. Here, we report eight cases of Klebsiella pneumoniae with bla NDM-1 in the neonatal ward of a teaching hospital in mainland China. Multilocus sequence typing showed that seven isolates were clonally related and confirmed them as sequence type 17 (ST17). One isolate belonged to ST433. These findings suggest continuous spread of bla NDM-1 in mainland China and emphasize the need for intensive surveillance and precautions.

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