281664-25-3

Upstream product

• 6298-96-0 1(R)-(4-methoxyphenyl)-ethylamine 
• 123-11-5 4-methoxy-benzaldehyde 
• 637-69-4 4-Methoxystyrene 
• 100-06-1 1-(4-methoxyphenyl)ethanone 
• 2393-23-9 4-methoxy-benzylamine 
• 170222-00-1 (S)-1-(4-methoxyphenyl)ethyl-1,3,2-benzodioxaborole 
• 2746-25-0 p-Methoxybenzyl bromide 

Downstream Products

• 281664-28-6 methyl (3S)-3-[(1R)-N-(4-methoxybenzyl)-1-(4-methoxyphenyl)ethylamino]-3-phenylpropanoate 
• 566930-75-4 4-methoxy-N-(4-methoxy-benzyl)-N-[1-(4-methoxy-phenyl)-ethyl]-benzamide 
• 566930-77-6 4-Methoxy-N-[(S)-1-(4-methoxy-phenyl)-ethyl]-N-[(R)-1-(4-methoxy-phenyl)-ethyl]-benzamide 

Relevant academic research and scientific papers

Protic additives or impurities promote imine reduction with pinacolborane

We report here that addition of stoichiometric amounts of alcohols or water to mixtures of imines and pinacolborane promote reduction reactions. The reactions of several imines were examined, revealing that alkyl imines were reduced, while aniline derived imines were not effectively reduced. The use of binol as an additive resulted in modest enantioinduction, however other chiral additives that were screened gave negligible enantioinduction. While the reactions described herein are not competitive in conversion with established imine reduction technologies, this work reveals that the presence of protic impurities must be considered as a promoter of side reactions in catalyzed imine hydroborations. Amines also promote imine reduction in certain cases, raising the possibility of a slow autocatalytic reaction. The ability of water or other protic impurities to promote the reduction of imines with pinacolborane represents an important identification of a potential source of background reaction in catalyzed reductions of imines.

CHIRAL CATALYST AND METHOD FOR ASYMMETRIC REDUCTION OF AN IMINE

The present disclosure discusses (i) a compound having a chemical formula according to Formula (I), or its enantiomer; and (ii) a compound that is reactive with a hydride to produce a compound having a chemical formula according to Formula (I), or its enantiomer. Formula (I) is: Formula (I) where R1 and R2 are H, optionally substituted C1-C3 alkyl, or linked together to form an optionally substituted C3 or C4 alkyl group; R3 and R3' are H; R4 and R4' are the same, and are optionally substituted C1-C6 alkyl; and R5 and R5' are the same, and are optionally substituted aryl or heteroaryl. In some examples, R4 and R5 are linked, and R4' and R5' are linked, where both linking groups are the same. The present disclosure also discusses methods of asymmetric reduction of an imine, and methods of forming the catalysts and pre-catalysts.

Enantioselective Imine Reduction Catalyzed by Phosphenium Ions

The first use of phosphenium cations in asymmetric catalysis is reported. A diazaphosphenium triflate, prepared in two or three steps on a multigram scale from commercially available materials, catalyzes the hydroboration or hydrosilylation of cyclic imin

Asymmetric Imine Hydroboration Catalyzed by Chiral Diazaphospholenes

The first use of diazaphospholenes as chiral catalysts has been demonstrated with enantioselective imine hydroboration. A chiral diazaphospholene prepared in a simple three-step synthesis from commercial materials has been shown to achieve the highest enantioselectivity for the hydroboration of alkyl imines with pinacolborane reported to date. Enantiomer ratios of up to 88:12 were obtained with low (2 mol %) catalyst loadings. Twenty examples of asymmetric reduction employing this main-group catalysis protocol, including the synthesis of the pharmaceuticals ent-rasagiline and fendiline, are shown.

Synthesis of α-methyl kainic acid by stereospecific lithiation-dearomatizing cyclization of a chiral benzamide

Stereospecific lithiation of N-α-methylbenzyl benzamides gives configurationally stable tertiary benzyllithiums which undergo a stereospecific dearomatizing cyclization with >99% retention of stereochemistry. The products are partially saturated isoindolinones which carry a new fully-substituted stereogenic centre. A ten-step sequence converts one of these products to the α-methyl analogue of kainic acid.

Catalytic asymmetric hydroboration/amination and alkylamination with rhodium complexes of 1,1′-(2-diarylphosphino-1-naphthyl)isoquinoline

Catecholboronate esters formed by asymmetric hydroboration of arylalkenes are not directly converted to amines by reaction with hydroxylamine-O-sulfonic acid. Prior conversion to a trialkylborane by reaction with ZnEt2 or MeMgCl permits a subsequent amination reaction to occur with essentially complete retention of configuration, leading to a range of primary α-arylalkylamines in up to 97% enantiomeric excess (ee). Secondary, but not tertiary amines may be formed by a related pathway when in situ generated alkylchloramines are employed as the aminating agent. The catalytic asymmetric hydroboration, β-alkylation and amination steps may be combined in a single stage. Overall, this provides a practical procedure for the synthesis of enantiomerically enriched arylamines, exemplified inter alia by the synthesis of (S)-1,2,3,4-tetrahydro-1-naphthylamine in 95-97% ee and of (R)-N-(cyclohexyl)-1′-(4-methoxyphenyl)ethylamine in 93 % ee.

A chiral, oxidatively cleavable auxiliary in conjugate additions of lithium amides. Preparation of enantiomerically pure β-amino acid derivatives

Addition of enantiomerically, pure 4-methoxyphanethyl-substituted lithium amides to α,β-unsaturated esters leads to β-amino acid derivatives 4 - 7 with selectivities > 95: 5. The auxiliary can be cleaved by oxidation with cerium(IV) ammonium nitrate (CAN) and subsequent hydrolysis of the resulting mixture of imines.