| Abstrakt: |
All four stereoisomers of 4-{4,5-dihydro-3H-dinaphtho[2,1-c:1′,2′-e]azepin-4-yl}dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine have been prepared from (R or S)-1,1′-binaphthyl-2,2′-diyl chlorophosphite and the appropriate dinaphtho-azepine. When reacted with [Rh(1,5-cyclooctadiene)2]BF4, highly active catalysts for the hydrogenation of α-dehydroamino acid esters were obtained. The highest enantioselectivities (up to 99 % ee) were achieved with the phosphoramidites having two chiral binaphthyl groups with opposite configurations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) |
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