Syntheses of Novel Chiral Monophosphines, 2,5-Dialkyl-7-phenyl-7-phosphabicycloheptanes, and Their Application in Highly Enantioselective Pd-Catalyzed Allylic Alkylation
Chiral Bicyclo[2.2.2]octane-Fused CpRh Complexes: Synthesis and Potential Use in Asymmetric C?H Activation
A new class of chiral cyclopentadienyl rhodium(I) complexes (CpRhI) bearing C2-symmetric chiral bridged-ring-fused Cp ligands was prepared. The complexes were successfully applied to the asymmetric C?H activation reaction of N-methoxybenzamides with quinones, affording a series of chiral hydrophenanthridinones in up to 82 % yield with up to 99 % ee. Interestingly, structure analysis reveals that the side wall of the optimal chiral CpRhI catalyst is vertically more extended, horizontally less extended, and closer to the metal center in comparison with the classic binaphthyl and spirobiindanyl CpRhI complexes, and may thus account for its superior catalytic performance.
Li, Guozhu,Yan, Xiaoqiang,Jiang, Jijun,Liang, Hao,Zhou, Chao,Wang, Jun
p. 22436 - 22440
(2020/10/15)
Highly enantioselective hydrogenation of simple ketones catalyzed by a Rh-PennPhos complex
Even alkyl methyl ketones undergo asymmetric hydrogenation with high enantioselectivity when a rhodium complex of the conformationally rigid chiral ligand 1 (Me-PennPhos; R = CH3) is used as the catalyst. Basic additives such as 2,6-lutidine contribute to the achievement of high enantiomeric excesses.
Syntheses of novel chiral 2,5-dialkyl-7-azabicyclo[2.2.1]heptanes and 2,5-dialkyl-7-thiobicyclo[2.2.1]heptanes
New C2-symmetric chiral amines with a rigid bicyclic framework have been synthesized via hydrogenation of monoazides catalyzed by 5% Pd/C in methanol. Enantiomerically pure 2,5-dialkyl-7-thiobicyclo[2.2.1]heptanes were made from readily available materials.