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[摘要]:Starting from readily available monosaccharides D-glucose and D-arabinose, a family of novel chiral diene and olefin-phosphinite hybrid ligands has been designed. These ligands were prepared by attaching phosphinite or allylic donor sites onto unsaturated carbohydrate scaffolds. In rhodium( I)-catalysed conjugate addition of boronic acids to enones, the olefin-phosphinite hybrids gave products in up to 99% ee and above, whereas the dienes only led to modest enantioselectivity. However, by shifting the allylic donor sites from position 4 of the pyranose to the anomeric centre, an unexpected reversal of the stereoinduction process was observed. |
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