A Family of Active Iridium Catalysts for Transfer Hydrogenation of Ketones

Clarke, Zaheer E.; Maragh, Paul T.; Dasgupta, Tara P.; Gusev, Dmitry G.; Lough, and Alan J.; Abdur‐Rashid, Kamaluddin

doi:10.1021/om060049z

Cited by 193 publications

(129 citation statements)

References 33 publications

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“…IrH 2 Cl[(iPr 2 PC 2 H 4 ) 2 NH] (2) was purchased from Strem (CAS 791629-96-4) or it was prepared according to the procedure of the literature. [16] All compounds were characterized by General procedure for the iridium-catalyzed amination of alcohols and diols A 37 mL-ACE-pressure tube (Aldrich; Z181072) was charged with the corresponding alcohol or diol (1 mmol), amine (3 mmol), and catalyst 2 (5.4 mg, 0.01 mmol). The reaction mixture was stirred at 120 8C or 140 8C for 20 h and the reaction monitored by GC.…”

Section: Methodsmentioning

confidence: 99%

Amination of Aliphatic Alcohols and Diols with an Iridium Pincer Catalyst

Andrushko

Roose³

et al. 2010

ChemCatChem

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Best aminated feature: Catalytic transformation of alcohols to amines is a fundamental transformation in synthetic organic chemistry. A general salt‐free Ir‐catalyzed amination of aliphatic alcohols and diols has been developed, which gives amino alcohols with high selectivity. By use of an Ir–pincer chlorodihydride complex, usually applied for the transfer hydrogenation of ketones, simple monoalcohols are aminated with excellent yields.

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Section: Methodsmentioning

confidence: 99%

Amination of Aliphatic Alcohols and Diols with an Iridium Pincer Catalyst

Andrushko

Roose³

et al. 2010

ChemCatChem

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“…The utility of complexes having the Ir-NH functionality, or other Ir-EH functionalities with mobile protons (e.g. Ir-OH with aminoalcohol ligands), has also been demonstrated and these systems are therefore proposed to operate through cycle A [29,32,40,54,92]. In a recent study of the ATH by formate catalyzed by Rh III and Ir III complexes in water, the activity was found to be highest at intermediate pH (ca.…”

Section: Scheme 61mentioning

confidence: 99%

Asymmetric hydrosilylation, transfer hydrogenation and hydrogenation of ketones catalyzed by iridium complexes

Malacea¹,

Poli²,

Manoury³

2010

Coordination Chemistry Reviews

329

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“…[8] Surprisingly, this rate is slightly higher than that of the analogous compound [RuCl(CNN)(dppb)] (TOF = 1.1 10 6 h À1 ), [6c] which is one of the most active TH catalysts, [9] and, in contrast to the ruthenium-based catalysts, 3 also displays high activity with only one equivalent of NaOiPr (TOF = 1.0 10 6 h À1 ). [10] are the only other systems which allow the TH of ketones at such low catalyst loadings.…”

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confidence: 99%

Osmium(II) CNN Pincer Complexes as Efficient Catalysts for Both Asymmetric Transfer and H₂ Hydrogenation of Ketones

et al. 2008

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Catalytic asymmetric hydrogenation (HY) and transfer hydrogenation (TH) of carbonyl compounds are usually performed with Ru, Rh, and Ir complexes, [1] and much less attention has been devoted to other transition-metal basedsystems. Although osmium complexes have occasionally been employed in the HY [2] and TH [3] of carbonyl compounds, we have recently shown that [OsCl 2 P 2 (Pyme)][4a] [P 2 = diphosphane; Pyme = 1-(pyridin-2-yl)methanamine)] complexes are extremely active catalysts in the TH of ketones, with reaction rates comparable to those of their Ru analogues.[4b] Owing to the stronger bonding of Os compared to Ru, robust and thermally stable chiral complexes can be obtained using a suitable set of ligands, which is a crucial breakthrough in achieving catalysts that display high productivity.[5] Since the CNN pincer complexes [RuCl(CNN)P 2 ][6] obtained from 1-(6-arylpyridin-2-yl)methanamines (HCNN) are among the most active catalysts for the TH of carbonyl compounds, we decided to investigate the chemistry of osmium complexes with CNN ligands and report herein the isolation of the first CNN pincer osmium derivatives [OsCl(CNN)P 2 ]. These complexes are extremely active and productive catalysts for both the TH and HY of ketones (turnover frequency (TOF) of up to 1.3 10 6 h À1 ). Moreover, asymmetric TH [7] and HY [1] have been achieved (ee values of up to 98 %) with a remarkably low loading (0.005-0.002 mol %) of the chiral version of these pincer complexes. Finally, the reversible nature of the ketone insertion into the Os À H bond suggests that Os-hydride and Os-alkoxide species are involved in TH and HY. Treatment of [OsCl 2 (PPh 3 ) 3 ] with 1 a (1.2 equiv) in 2-propanol in the presence of the weak base NEt 3 at reflux for 2 h affords the CNN pincer complex 2 [8] in 94 % yield (Scheme 1). The 31 P NMR spectrum of 2 shows two doublets at d = 7.1 and À1.6 ppm with a 2 J P,P coupling constant of 15.7 Hz, which is typical for a cis OsP 2 arrangement. The singlet at d = 7.95 ppm in the 1 H NMR spectrum is due to the CH proton close to the orthometalated carbon. Complex 3[8] is easily obtained in high yield upon treatment of [OsCl 2 (PPh 3 ) 3 ] with Ph 2 P(CH 2 ) 4 PPh 2 (dppb) and then with 1 a in the presence of NEt 3 (Scheme 1). The NCH 2 group gives a 13 C NMR signal at d = 54.8 ppm ( 3 J C,P = 2.6 Hz), whereas the orthometalated carbon appears at d = 161.5 ppm ( 2 J C,P = 9.0 and 3.9 Hz). The chiral pincer complex 4 was prepared in a similar manner to 3 but with dppb in combination with 1 b (85 % yield), whereas 5 and 6 (55 and 47 % yield, respectively) were obtained from (S,R)-Josiphos with 1 a and 1 c, respectively (Scheme 1).[8] 31 P NMR spectroscopic control experiments revealed the formation of different isomers in the reaction mixtures; the predominant stereoisomer was isolated from the reaction mixtures.The osmium derivatives 2-6 were found to be highly active catalysts for the TH of different ketones 7 (0.1m) in basic 2-propanol (Scheme 2). Thus, fast reduction of acetophenone (7 a) into 1-pheny...

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A Family of Active Iridium Catalysts for Transfer Hydrogenation of Ketones

Cited by 193 publications

References 33 publications

Amination of Aliphatic Alcohols and Diols with an Iridium Pincer Catalyst

Amination of Aliphatic Alcohols and Diols with an Iridium Pincer Catalyst

Asymmetric hydrosilylation, transfer hydrogenation and hydrogenation of ketones catalyzed by iridium complexes

Osmium(II) CNN Pincer Complexes as Efficient Catalysts for Both Asymmetric Transfer and H₂ Hydrogenation of Ketones

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A Family of Active Iridium Catalysts for Transfer Hydrogenation of Ketones

Cited by 193 publications

References 33 publications

Amination of Aliphatic Alcohols and Diols with an Iridium Pincer Catalyst

Amination of Aliphatic Alcohols and Diols with an Iridium Pincer Catalyst

Asymmetric hydrosilylation, transfer hydrogenation and hydrogenation of ketones catalyzed by iridium complexes

Osmium(II) CNN Pincer Complexes as Efficient Catalysts for Both Asymmetric Transfer and H2 Hydrogenation of Ketones

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Osmium(II) CNN Pincer Complexes as Efficient Catalysts for Both Asymmetric Transfer and H₂ Hydrogenation of Ketones