Palladium-catalyzed asymmetric hydrogenation of simple ketones activated by Brønsted acids

Zhou, Xiaoyu; Wang, Duo‐Sheng; Bao, Ming; Zhou, Yong‐Gui

doi:10.1016/j.tetlet.2011.03.057

Cited by 36 publications

(8 citation statements)

References 64 publications

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“…The reason is not clear. We can only cite similar observations in Pd‐catalyzed hydrogenations of prochiral ketones4c and 2,5‐disubstituted pyrroles 3a. It is noteworthy that oxime ( E )‐ 1e reveals very low reactivity which may be ascribed to significant stabilization of the iminium intermediate by a mesomeric effect of the MeO group.…”

Section: Resultsmentioning

confidence: 86%

Palladium‐Catalyzed Asymmetric Hydrogenation of N‐Hydroxy‐α‐imino Phosphonates Using Brønsted Acid as Activator: The First Catalytic Enantioselective Approach to Chiral N‐Hydroxy‐α‐amino Phosphonates

et al. 2012

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The enantioselective synthesis of ring-substituted [N-(hydroxy)amino]A C H T U N G T R E N N U N G (phenyl)methylphos-A C H T U N G T R E N N U N G phonic esters via asymmetric hydrogenation of the corresponding N-hydroxy-a-imino phosphonates with up to 90% ee was developed using catalytic amounts of palladium(II) acetate and (R)-BINAP in 2,2,2-trifluoroethanol with a Brønsted acid as an activator.

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Section: Resultsmentioning

confidence: 86%

Palladium‐Catalyzed Asymmetric Hydrogenation of N‐Hydroxy‐α‐imino Phosphonates Using Brønsted Acid as Activator: The First Catalytic Enantioselective Approach to Chiral N‐Hydroxy‐α‐amino Phosphonates

et al. 2012

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“…39 Using catalytic amount of Brønsted acid as an activator, Zhou and co-workers recently disclosed a homogeneous Pd-catalyzed asymmetric hydrogenation of simple ketones 31 with up to 88% ee (Scheme 22). 40 Salicylic acid was found to be the best activator in terms of activity and enantioselectivity. Low conversions were observed when much stronger acids (TFA or TsOH) were used as additives.…”

Section: Palladium Catalyzed Asymmetric Hydrogenation Of Ketonesmentioning

confidence: 99%

Homogeneous palladium-catalyzed asymmetric hydrogenation

et al. 2013

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The transition metal catalyzed asymmetric hydrogenation of unsaturated compounds arguably presents one of the most attractive methods for the synthesis of chiral compounds. Over the last few decades, Pd has gradually grown up as a new and popular metal catalyst in homogeneous asymmetric hydrogenation the same as traditional Ru, Rh and Ir catalysts. Much progress has been successfully achieved in the asymmetric reduction of imines, enamines, olefins, ketones and heteroarenes. It was also found that palladium catalyzed asymmetric hydrogenation could be used as a key step in tandem reactions to quickly synthesize chiral compounds. This tutorial review intends to offer an overview of recent progress in homogeneous palladium catalyzed asymmetric hydrogenation and should serve as an inspiration for further advances in this area. Key learning points(1) The general mechanism for homogeneous palladium catalyzed asymmetric hydrogenation.(2) The palladium catalysts' tolerance against acid, water and air in the hydrogenation process.(3) The substrate scopes and limitations in these transformations. (4) The common hydrogen sources used in these catalytic systems.(5) The general solvent-dependent phenomena in these transformations.

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“…In this context, the group of Zhou has reported the first example of highly enantioselective palladium‐catalyzed asymmetric hydrogenation of functionalized ketones with ( R , R )‐Me‐Duphos as chiral ligand (Figure 1). [5a] They have explored this kind of reactions thereafter by the strategies such as dynamic kinetic resolution, desymmetrization, and the employing of Brønsted acids [5b–d] . Zhang and co‐workers have studied the palladium‐catalyzed asymmetric hydrogenation of α‐acyloxy‐1‐arylethanones and α‐phthalimide ketones with excellent results [6] .…”

Section: Figurementioning

confidence: 99%