First enantioselective organocatalytic allylation of simple aldimines with allyltrichlorosilane

Jagtap, Sunil B.; Tsogoeva, Svetlana B.

doi:10.1039/b611823b

Cited by 50 publications

(15 citation statements)

References 22 publications

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“…Fractions containing N-formyl-L-proline were pooled, and the solvent was removed under reduced pressure to yield the product (4.5 g, 90%) as a clear oil. 1 30 D-Proline (600 mg, 5.21 mmol) was dissolved in 85% HCO 2 H (11 mL) and cooled to 0 °C. Ac 2 O (3.6 mL) was added and the resulting mixture was stirred at r.t. for 2 h. Ice cold H 2 O (4.2 mL) was then added and the solvent was removed under reduced pressure.…”

Section: N-(4-chlorophenyl)-1-[4-(trifluoromethyl)phenyl]ethanamine (mentioning

confidence: 99%

Asymmetric Transfer Hydrogenation of Ketimines with Trichlorosilane: Structural Studies

Zhang¹,

Rooshenas²,

Hausmann³

et al. 2009

Synthesis

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A s y m m e t r i c T r a n s f e r H y d r o g e n a t i o n o f K e t i m i n e s w i t h T r i c h l o r o s i l a n e Abstract: We report structural and mechanistic studies on the organocatalytic asymmetric transfer hydrogenation of ketimines with trichlorosilane. Amines were obtained in good yields and moderate enantioselectivities. Both experiment and computation were utilized to provide an improved understanding of the mechanism.The importance of chiral amines lies in their propensity to be fundamentally important building blocks of natural products, drugs, as well as agrochemicals. 1 The asymmetric reduction of imines with a chiral catalyst represents a direct and most appealing approach to enantiomerically enriched amines and the development of asymmetric catalysts for such processes has been the focus of recent research efforts. 2 However, in contrast to the well-developed, effective, and industrially relevant asymmetric reductions of olefins and ketones, the corresponding imine reductions are less advanced. 3 Among various catalytic methods, hydrogenation or transfer hydrogenation of ketimines with a chiral transition metal catalyst system is currently one of the most accessible protocols. 4 Parallel to the quest for more efficient metal catalysts, the discovery of 'green' catalysts has become another focal point. 5 As a consequence, impressive progress has been made recently in the development of organic catalysts for the enantioselective transfer hydrogenation of ketimines using Hantzsch dihydropyridine or trichlorosilane as the hydride donor in conjunction with a chiral organocatalyst that activates the substrate or the reductant (Scheme 1). 6-16 Scheme 1 Organocatalytic asymetric transfer hydrogenation of iminesOur studies revealed that electron-poor thiourea derivatives can activate imines by hydrogen bonding and thus promote the hydrogen transfer from Hantzsch esters to generate amines, but the substrate scope was limited to aliphatic and aromatic aldimines. 17 Unfortunately, chiral thiourea derivatives fail to promote the hydride transfer from Hantzsch esters to ketimines. As part of our efforts in the development of organocatalytic methods for the reduction of ketimines, we turned our attention to trichlorosilane as an alternative organic reducing agent. 18 Inspired by the reduction of aldehydes, ketones, as well as imines with the combination of trichlorosilane and N,Ndimethylformamide, the Matsumura group were the first to develop chiral N,N-dimethylformamide analogues, namely N-formylproline derivatives, as effective activators for asymmetric reductions of ketimines using trichlorosilane as the reducing agent, giving the corresponding amines in moderate enantiomeric excess. 9 Later, significant improvement of the enantiomeric excess was achieved by Malkov et al. by using a new N-methyl-L-valine derived Lewis basic organocatalyst. 12 Since then, considerable efforts have been devoted to the development of this transformation and a rapid evolution of catalyst structures has been made by Matsum...

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Section: N-(4-chlorophenyl)-1-[4-(trifluoromethyl)phenyl]ethanamine (mentioning

confidence: 99%

Asymmetric Transfer Hydrogenation of Ketimines with Trichlorosilane: Structural Studies

Zhang¹,

Rooshenas²,

Hausmann³

et al. 2009

Synthesis

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“…3C). The poor to insignicant yield of N-formylated product in solvents such as THF, MeOH, DCE and toluene compared to DMF, DMA or ACN highlighted the critical role of in situ formed formoxy borohydride species for the success of the N-formylation (Table 1, entry [4][5][6][7][8].…”

Section: Resultsmentioning

confidence: 99%

“…1). Formamides hold promise as solvents and organocatalysts 5,6 and are the valuable raw material for various heterocycles, [7][8][9] formamidines, 10,11 as well as isocyanides. 12,13 Formamides can also be exploited as surrogates of isocyanates for the synthesis of ureas and carbamates.…”

Section: Introductionmentioning

confidence: 99%

Catalyst free N-formylation of aromatic and aliphatic amines exploiting reductive formylation of CO₂ using NaBH₄

Kumar

Sharma

et al. 2021

RSC Adv.

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“…44 The more immediate allylating agent is, in fact, l-proline derivative (19), formed in situ, and observed by NMR and MS.…”

Section: Addition Of Organometallicsmentioning

confidence: 99%

Reactions of Aldehydes and Ketones and their Derivatives

Murray

2010

Organic Reaction Mechanisms · 2006

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First enantioselective organocatalytic allylation of simple aldimines with allyltrichlorosilane

Abstract: A new organocatalytic system, novel chiral bisformamide and in situ generated L-proline-derived allylsilane reagent , which converts different aldimines to homoallylic amines in good to high yields (up to 95%) and good enantioselectivities (up to 85% ee) has been described.

Cited by 50 publications

References 22 publications

Asymmetric Transfer Hydrogenation of Ketimines with Trichlorosilane: Structural Studies

Asymmetric Transfer Hydrogenation of Ketimines with Trichlorosilane: Structural Studies

Catalyst free N-formylation of aromatic and aliphatic amines exploiting reductive formylation of CO₂ using NaBH₄

Reactions of Aldehydes and Ketones and their Derivatives

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First enantioselective organocatalytic allylation of simple aldimines with allyltrichlorosilane

Abstract: A new organocatalytic system, novel chiral bisformamide and in situ generated L-proline-derived allylsilane reagent , which converts different aldimines to homoallylic amines in good to high yields (up to 95%) and good enantioselectivities (up to 85% ee) has been described.

Cited by 50 publications

References 22 publications

Asymmetric Transfer Hydrogenation of Ketimines with Trichlorosilane: Structural Studies

Asymmetric Transfer Hydrogenation of Ketimines with Trichlorosilane: Structural Studies

Catalyst free N-formylation of aromatic and aliphatic amines exploiting reductive formylation of CO2 using NaBH4

Reactions of Aldehydes and Ketones and their Derivatives

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Catalyst free N-formylation of aromatic and aliphatic amines exploiting reductive formylation of CO₂ using NaBH₄