Asymmetric Hydroboration of Heteroaryl Ketones by Aluminum Catalysis

Lebedev, Yury; Polishchuk, I. E.; Maity, Bholanath; Guerreiro, Miguel Dinis Veloso; Cavallo, Luigi; Rueping, Magnus

doi:10.1021/jacs.9b10364

Cited by 45 publications

(31 citation statements)

References 56 publications

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“…15 Rueping et al reported the first asymmetric hydroboration of ketones using aluminum complexes bearing chiral biphenol-type ligands. 16 These results serve as evidence that tailor-made aluminum hydride complexes exhibit transition-metal like reactivity in mediating catalytic reduction of unsaturated polar bonds (C=O, C=N) and C-C multiple bonds. Despite these pertinent recent developments, the implementation of aluminum hydride complexes for catalytic CO 2 transformation into value-added chemicals has not been reported.…”

Section: Introductionmentioning

confidence: 81%

Aluminum-Hydride-Catalyzed Hydroboration of Carbon Dioxide

et al. 2021

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This study describes the first use of a bis(phosphoranyl)methanido aluminum hydride, [ClC(PPh 2 NMes) 2 AlH 2 ] (2, Mes = Me 3 C 6 H 2 ) for the catalytic hydroboration of CO 2 . Complex 2 was synthesized by the reaction of a lithium carbenoid [Li(Cl)C(PPh 2 NMes) 2 ] with two equivalents of AlH 3 •NEtMe 2 in toluene at -78 o C. 10 mol % of 2 was able to catalyze the reduction of CO 2 with HBpin in C 6 D 6 at 110 o C for 2 days to afford a mixture of methoxyborane [MeOBpin] (3a; yield: 78 %, TOF: 0.16 h -1 ) and bis(boryl)oxide [pinBOBpin] (3b). When more potent [BH 3 •SMe 2 ] was used instead of HBpin, the catalytic reaction was extremely pure, resulting in the formation of trimethyl borate [B(OMe) 3 ] (3e) [catalytic loading: 1 mol % (10 mol %); reaction time: 60 min (5 min); yield: 97.6 % (>99 %); TOF: 292.8 h -1 (356.4 h -1 )] and B 2 O 3 (3f). Mechanistic studies show that the Al-H bond in complex 2 activated CO 2 to form [ClC(PPh 2 NMes) 2 Al(H){OC(O)H}] (4), which was subsequently reacted with BH 3 •SMe 2 to form 3e and 3f, along with the regeneration of complex 2. Complex 2 also shows good catalytic activity towards hydroboration of carbonyl, nitrile and alkyne derivatives. ASSOCIATED CONTENTSupporting Information. The Supporting Information is available free of charge on the ACS Publications website.Experimental procedures (PDF), theoretical studies (XYZ) X-ray crystallographic data (CIF)

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Section: Introductionmentioning

confidence: 81%

Aluminum-Hydride-Catalyzed Hydroboration of Carbon Dioxide

et al. 2021

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“…Given this background, Rueping and coworkers developed the BINOL-ligated aluminum complex-catalyzed enantioselective hydroboration of a wide range of 2-pyridine ketones and analogous heterocyclic ketones. [46] This work represents the first asymmetric hydroboration of prochiral ketones catalyzed by chiral aluminum complexes.…”

Section: Other (M = Al)mentioning

confidence: 99%

Recent Advances in Metal‐Catalyzed Asymmetric Hydroboration of Ketones

Wang

Park

2021

ChemCatChem

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Metal-catalyzed asymmetric reduction of unsaturated functions is a highly useful and fundamental transformation to give diverse chiral synthons. In particular, the enantioselective reduction of prochiral ketones is of great synthetic interest, since it can provide optically active chiral alcohols which have wide applications in organic synthesis, materials science, and pharmaceutical chemistry. Numerous and diverse metal catalytic systems for asymmetric hydrogenation and hydrosilylation of ketones extensively evolved in terms of activity, selectivity, and practicality, while only limited varieties of metal catalysts for the asymmetric hydroboration had been documented until 2010. Diverse and new metal complexes with a range of multidentate chiral ligands have recently emerged as catalysts for the enantioselective ketone hydroboration, which are highly differentiated from the precedence in several aspects. This Minireview summarizes recent examples of the metal catalyst systems for the asymmetric hydroboration of ketones published from 2015 to 2020. Diverse catalytic working modes involved in a process of enantiodifferentiating hydride transfer, are discussed with a strong emphasis on the steric and electronic effects of chiral ligands.

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“…Enantioselective hydroboration is a common, efficient, and safe method to produce optically enantiopure secondary alcohols from ketones. Metal-based catalytic enantioselective hydroborations of ketones were developed using Co complexes bearing iminopyridine oxazoline ligands, Mn complexes bearing bis(oxazolinylmethylidene)-isoindoline pincer ligands, Ni complexes bearing oxazoline ligands, or Mg and Al complexes bearing BINOLs as the catalytic system; meanwhile RE-based complexes combined with N , N ′-dioxide ligands, phenoxy-functionalized prolinolates, or Trost ligands were also employed in the transformation. Though enantioselective hydroboration is a reaction that has attracted much attention, highly efficient systems are still rare and need to be constantly developed, because the target enantiopure secondary alcohols are key organic synthesis intermediates .…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Hydroboration of Ketones Catalyzed by Rare-Earth-Metal Complexes Supported with Phenoxy-Functionalized TsDPEN Ligands

Zhao

2021

Organometallics

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Six novel chiral rare-earth-metal complexes bearing the phenoxy-functionalized TsDPEN ligandwere synthesized successfully and well characterized. The solid-state structures of four tetranuclear rare-earth-metal complexes [RE 2 L 1 3 ] 2 (RE = Nd (1), Sm (2), Eu (3), Gd ( 4)) and the dual-core yttrium complex Y 2 L 1 3 (5) were determined by X-ray diffraction, respectively. The structure of lanthanum complex 6 was speculated by the 1 H DOSY spectroscopy in THF-d 8 together with DFT calculations. Complexes 1−5 were employed to catalyze the enantioselective hydroboration of ketones and α,β-unsaturated ketones using pinacolborane (HBpin) as a reductant, and complex 1 gave better outcomes in comparison to the others. The corresponding secondary alcohols were obtained in excellent yields and moderate ee values. The same results were also achieved using the combined catalyst system of the neodymium amide Nd[N(SiMe 3 ) 2 ] 3 with the phenoxy-functionalized TsDPEN ligand H 3 L 1 in a 1:1.5 molar ratio.

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Asymmetric Hydroboration of Heteroaryl Ketones by Aluminum Catalysis

Cited by 45 publications

References 56 publications

Aluminum-Hydride-Catalyzed Hydroboration of Carbon Dioxide

Aluminum-Hydride-Catalyzed Hydroboration of Carbon Dioxide

Recent Advances in Metal‐Catalyzed Asymmetric Hydroboration of Ketones

Enantioselective Hydroboration of Ketones Catalyzed by Rare-Earth-Metal Complexes Supported with Phenoxy-Functionalized TsDPEN Ligands

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