Novel phosphine–phosphites and their use in asymmetric hydrogenation

Excellent enantioselectivities and activities have been obtained in the rhodium catalyzed asymmetric hydrogenation of dimethyl itaconate and several dehydroamino acid esters using a new class of BINOL based phosphine–phosphite ligand. The hydrogenation proceeded efficiently even at a substrate/catalyst molar ratio of 10,000 to give the product with 100% conversion and 99.1% enantioselectivity.

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(2R,4S)-2-Diphenylphosphino-4-{(S)-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-2-yloxy}-pentaneC37H32O3P2[α]D = +336.6 (c 1.135, CH2Cl2)Source of chirality: (S)-H0-Binol, (2R,4R)-pentane-2,4-diol and stereoselective synthesis

(2S,4R)-2-Diphenylphosphino-4-{(S)-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-2-yloxy}-pentaneC37H32O3P2[α]D = +344.8 (c 1.05, CH2Cl2)Source of chirality: (S)-H0-Binol, (2S,4S)-pentane-2,4-diol and stereoselective synthesis

(2S,4R)-2-Diphenylphosphino-4-{(S)-5,5′,6,6′,7,7′,8,8′-octahydro-dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-2-yloxy}-pentaneC37H40O3P2[α]D = +185.9 (c 1.135, CH2Cl2)Source of chirality: (S)-H8-Binol, (2R,4R)-pentane-2,4-diol and stereoselective synthesis