Novel Spiro Phosphinite Ligands and Their Application in Homogeneous Catalytic Hydrogenation Reactions J. Am. Chem. Soc. 1997, 119, 9570−9571

Chan, Albert S. C.; Hu, Wenhao; Pai, Cheng‐Chao; Lau, Chak Po; Jiang, Yaozhong; Mi, Aiqiao; Yan, Ming; Sun, Jianguo; Lou, and Rongliang; Deng, Jingen

doi:10.1021/ja985517d

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“…Chiral ligands 88 [81], 89 and 90 [82] with rigid backbones were found to be less effective in Rh-catalyzed hydrogenation reactions. In 1997, we introduced the novel ligand SpirOP (91 and 92) based on a rigid spiro backbone which mimics the binaphthyl rings in BINAP in its most effective state (skewed position), giving rise to an eight-membered chelate ring [27,83]. Indeed, the desired hydrogenation product 2-acetamidopropionic acid was obtained in > 99.9% ee, with complete conversion in 10 min using Rh-SpirOP.…”

Section: Ar = Ph R = Hmentioning

confidence: 99%

Bidentate Ligands Containing a Heteroatom–Phosphorus Bond

Kok

Au‐Yeung

Cheung

et al. 2006

The Handbook of Homogeneous Hydrogenation

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Bidentate phosphorus ligands containing one or more heteroatom-phosphorus bonds are of high interest because they are relatively easy to prepare, and because a huge multitude of inexpensive, commercially available chiral diols, diamines, amino alcohols and amino acids can serve as the scaffold. Although the heteroatoms in these scaffolds are usually electronegative in nature, the reactivity and enantioselectivity of the metal complexes based on some of these ligands are quite remarkable, and sometimes even surpass those of the complexes based on electron-rich phosphines. This chapter compiles the comprehensive data concerning the asymmetric hydrogenation of various prochiral olefins mediated by the rhodium(I) complexes of this class of chiral ligands. Aminophosphine-Phosphinites (AMPPs)The ease of synthesis from chiral amino alcohols with a wide array of derivatives in one step established its good potential in the field of asymmetric catalysis. The general preparation of "semi-symmetrical" AMPPs involves the nucleophilic attack of two equivalents of chlorophosphine in the presence of a base (Fig. 27.1). A "mixed" AMPP can also be prepared by virtue of the fact that phosphorus-based electrophiles have a strong preference for hydroxy over secondary amine or amide. Clearly, this synthetic method allows the preparation of a large variety of AMPP ligands with adjustable electronic and steric properties. Agbossou recently reviewed the state of the art of AMPPs [1]. In consideration to the modern high-throughput methods, this approach allowed a rapid combinatorial screening of various catalysts and reactions.In general, applications of AMPP have concentrated on the asymmetric hydrogenation of functionalized olefins, especially dehydroamino acids. Among 883The Handbook of Homogeneous Hydrogenation. Edited by J. G. de Vries and C. J. Elsevier

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