98359-08-1

Upstream product

• 98-86-2 acetophenone 
• 100-46-9 benzylamine 
• 100-52-7 benzaldehyde 
• 618-36-0 rac-methylbenzylamine 

Downstream Products

• 119022-25-2 1-Benzyl-4-hydroxy-3,6-diphenyl-1H-pyridin-2-one 
• 38235-77-7 (R)-N-benzyl-1-phenylethylamine 
• 3193-62-2 N-benzyl-1-phenylethylamine 
• 17480-69-2 (S)-N-benzyl-1-phenylethylamine 
• 119406-09-6 meso-N_.N'-Dibenzyl-1.2-diphenyl-1.2-dimethyl-1.2-diaminoethan 
• 98-86-2 acetophenone 
• 100-46-9 benzylamine 
• 279668-69-8 N-benzyl-2,2,2-trichloro-N-(1-phenyl-vinyl)-acetamide 

Relevant academic research and scientific papers

Ruthenium-catalyzed transfer hydrogenation of imines by propan-2-ol in benzene

Transfer hydrogenation of a variety of different imines to the corresponding amines by propan-2-ol in benzene catalyzed by [Ru2(CO)4(μ H)(C4Ph4COHOCC4Ph4)] (1) has been studied. The reaction is highly efficient with turnover frequencies of over 800 per hour, and the product amines were obtained in excellent yields. A remarkable concentration dependence of propan-2-ol was observed when the reaction was run in benzene as cosolvent. An optimum was obtained at 24 equivalents of propan-2-ol to imine, and further increase of the propan-2-ol led to a dramatic decrease in rate. Also the use of polar cosolvents with 24 equivalents of propan-2-ol gave a low rate. It was found that ketimines react faster than aldimines and that electron-donating substituents on the imine increase the rate of the catalytic transfer hydrogenation. Electron-withdrawing substituents decreased the rate. An isomerization was observed with imines having an α-hydrogen at the N-alkyl substituent, which is in accordance with a mechanism involving a ruthenium-amine intermediate. It was demonstrated that the ruthenium-amine complex from α-methylbenzylamine, corresponding to the postulated intermediate, can replace 1 as catalyst in the transfer hydrogenation of imines. A primary deuterium isotope effect of kCH/CD = 2.7 ± 0.25 was observed when 2-deuterio-propan-2-ol vas used in place of propan-2-ol in the ransfer hydrogenation of N-phenyl-(1-phenylethylidene)amine.

Enantioselective reduction of: N -alkyl ketimines with frustrated Lewis pair catalysis using chiral borenium ions

Enantioselective reduction of ketimines was demonstrated using chiral N-heterocyclic carbene (NHC)-stabilised borenium ions in frustrated Lewis pair catalysis. High levels of enantioselectivity were achieved for substrates featuring secondary N-alkyl substituents. Comparative reactivity and mechanistic studies identify key determinants required to achieve useful enantioselectivity and represent a step forward in the further development of enantioselective FLP methodologies.

New synthetic access to 3-fluoroalkyl-5-pyrazolecarboxylates and carboxylic acids

A novel process for preparing 3-fluoroalkyl-5-pyrazolecarboxylates and carboxylic acids is hereby presented. Easily accesible α-fluorinated ketimines were condensed with oxalyl monochloride derivatives, and the obtained vinamides underwent acid-catalyzed cyclization with substituted hydrazines. This highly efficient protocol can also be used for non-fluorinated C-3 and C-5 substituents.

Efficient Synthesis of Amines by Iron-Catalyzed C=N Transfer Hydrogenation and C=O Reductive Amination

Here we report the catalytic transfer hydrogenation (CTH) of non-activated imines promoted by a Fe-catalyst in the absence of Lewis acid co-catalysts. Use of the (cyclopentadienone)iron complex 1, which is much more active than the classical ‘Kn?lker complex’ 2, allowed to reduce a number of N-aryl and N-alkyl imines in very good yields using iPrOH as hydrogen source. The reaction proceeds with relatively low catalyst loading (0.5–2 mol%) and, remarkably, its scope includes also ketimines, whose reduction with a Fe-complex as the only catalyst has little precedents. Based on this methodology, we developed a one-pot CTH protocol for the reductive amination of aldehydes/ketones, which provides access to secondary amines in high yield without the need to isolate imine intermediates. (Figure presented.).

Experimental analysis of the catalytic cycle of the borane-promoted imine reduction with hydrosilanes: Spectroscopic detection of unexpected intermediates and a refined mechanism

The discovery of intermediates that had not been seen before in imine reduction involving borane-mediated Si-H bond activation provided new insight into the mechanism, eventually leading to a refined catalytic cycle that also bears relevance to asymmetric variants. The catalysis proceeds through an ion pair composed of a silyliminium ion and a borohydride that subsequently reacts to yield an N-silylated amine and the borane catalyst. The latter step is enantioselectivity-determining when using a chiral borane. It was now found that there are additional intermediates that profoundly influence the outcome of such enantioselective transformations. Significant amounts of the corresponding free amine and N-silylated enamine are present in equimolar ratio during the catalysis. The free amine emerges from a borohydride reduction of an iminium ion (protonated imine) that is, in turn, generated in the enamine formation step. The unexpected alternative pathway adds another enantioselectivity-determining hydride transfer to reactions employing chiral boranes. The experiments were done with an axially chiral borane that was introduced by us a few years ago, and the refined mechanistic picture helps to understand previously observed inconsistencies in the level of enantioinduction in reductions catalyzed by this borane. Our findings are general because the archetypical electron-deficient borane B(C6F5)3 shows the same reaction pattern. This must have been overlooked in the past because B(C 6F5)3 is substantially more reactive than our chiral borane with just one C6F5 group. Reactions with B(C6F5)3 must be performed at low catalyst loading to allow for detection of these fundamental intermediates by NMR spectroscopy.

Asymmetric hydrogenation of N-alkyl and N-aryl ketimines using chiral cationic Ru(diamine) complexes as catalysts: The counteranion and solvent effects, and substrate scope

Asymmetric hydrogenation of N-alkyl and N-aryl ketimines catalyzed by chiral cationic η6-arene-(N-monosulfonylated diamine) Ru(II) complexes has been investigated. Strong counteranion and solvent effects on the enantioselectivity were observed. The ruthenium catalyst bearing non-coordinating BArF- anion was found to be particularly effective for the hydrogenation of acyclic and exocyclic N-alkyl ketimines in the presence of (Boc)2O in dichloromethane or even under solvent-free conditions, providing chiral amines with up to >99% ee and full conversions. Alternatively, the ruthenium catalyst bearing achiral phosphate anion together with corresponding phosphoric acid as the additive was also efficient for the hydrogenation of N-alkyl ketimines in the absence of (Boc)2O with excellent enantioselectivities and full conversions. For N-aryl ketimines lower enantiomeric excesses were observed by using the ruthenium catalyst bearing BArF- anion. This catalytic protocol thus provides a facile and practical access to optically active amines and has been successfully employed in the gram-scale synthesis of enantiomerically pure (+)-sertraline.

Asymmetric hydrogenation of N-Alkyl ketimines with phosphine-free, chiral, cationic Ru-MsDPEN catalysts

(Solvent) free and easy: A phosphine-free, chiral, cationic Ru-MsDPEN complex [(S,S)-1] is found to be an efficient catalyst for the enantioselective hydrogenation of a range of often-problematic N-alkyl ketimines (see scheme). This new method provides a more practical and greener synthetic approach to optically active amines, particularly N-alkyl amines, such as Sertraline.

Activation of the Si-B Linkage: Copper-Catalyzed addition of nucleophilic silicon to imines

Activation of the Si-B bond through copper-catalyzed transmetalation quickly developed into a practical method to generate Cu-Si reagents These silicon nucleophiles cleanly add to aldehyde-derived imine electrophiles to form R-silylated amines in protic media, and no carbon-tonitrogen Brook-type rearrangement of the intermediate anion is observed. Aside from electron-withdrawing groups at the imine nitrogen atom, for example, SO2Tol and P(O)Ph2, previously delicate nitrogen substituents such as phenyl or benzhydryl are tolerated. The same protocol also allows the unprecedented addition to representative ketone-derived imines.

A highly enantioselective organocatalytic method for reduction of aromatic N-alkyl ketimines

A study has demonstrated the development of a highly enantioselective catalytic method for the reduction of aromatic N-alkyl ketimines by trichlorosilane under mild conditions using the newly designed Lewis base organocatalyst that incorporates C- and S-chirality. The S-chiral sulfinamide group in these catalysts plays a crucial role similar to the carboxamide groups as Lewis base for the activation of HSiCl3, and also serves as a source of chirality that the carboxamide group lacks for the asymmetric induction. The results of the study showed that excellent enantioselectivities of up to 99.6% ee and high yields were obtained for a wide range of substrates. Further works is also in progress to clarify the mechanism of the transformation and explore the full application scope of the present catalyst system.

Rh(I)-catalyzed solvent-free ortho-alkylation of aromatic imines under microwave irradiation

The synthesis of ortho-alkylated ketones through a chelation-assisted Rh (I) catalyzed ortho-alkylation reaction of aromatic imines under microwave activated solvent-free conditions in monomode reactors was performed. These conditions have been also applied to hydroacylation and ortho-alkylation reactions with aldimines.