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Upstream product

• 67174-26-9 diphenyl N-<2-phenyl-1-(1-pyrrolidinyl)propylidene>phosphoramidate 
• 148932-08-5 α-Pyrrolidino-β-methyl styrene 
• 26386-88-9 diphenyl phosphoryl azide 
• 123-75-1 pyrrolidine 
• 100-42-5 styrene 
• 201230-82-2 carbon monoxide 
• 98-83-9 isopropenylbenzene 
• 34713-70-7 2-Phenylpropanal 

Relevant academic research and scientific papers

Anthracene-rhodium complexes with metal coordination at the central ring-a new class of catalysts for reductive amination

A new class of anthracene complexes with a metal coordinated at the central ring was applied in catalysis for the first time. As a result, a simple and efficient protocol for reductive amination that involves CO as a reducing agent has been developed. The rhodium complex [(cyclooctadiene)Rh(C10H4Me2(OMe)4)]+ (1 mol%) catalyses such reactions under mild conditions (40-130 °C) and produces a variety of amines in good yields (74-95%) without affecting the functional groups. The protocol is acceptable for all combinations of aldehydes (aromatic and aliphatic), ketones (aromatic and aliphatic) and amines (aromatic and aliphatic; primary and secondary).

Synthesis of β-Chiral Amines by Dynamic Kinetic Resolution of α-Branched Aldehydes Applying Imine Reductases

Imine reductases (IREDs) allow the one-step preparation of optically active secondary and tertiary amines by reductive amination of ketones. Until now, mainly α-chiral amines have been prepared by this route. In this study, we explored the possibility of synthesizing β-chiral amines, a class of compounds which is also frequently found as structural motif in pharmaceuticals but much more challenging to prepare due to the following reasons: (i) The aldehyde substrate already contains the chiral center and needs to be racemized to enable full conversion. (ii) Because the intermediate imine bears the stereo center two carbon atoms remote to the imine nitrogen, it is more challenging to achieve high enantioselectivity compared to α-chiral amine synthesis. For investigating the proof of concept, we first confirmed that different IREDs are able to convert a variety of α-branched aldehydes when combined with five different amine substrates. The IRED from Streptomyces ipomoeae was a suitable enzyme facilitating the dynamic kinetic resolution of 2-phenylpropanal and a substituted 2-methyl-3-phenylpropanal: the corresponding N-methylated β-chiral amines were obtained with '95 % conversion and 78 and 95 %ee. Other amines were formed with low to moderate enantiomeric excess. This exemplifies the potential of IREDs for the one-step synthesis of secondary β-chiral amines, but also the challenge to identify highly selective enzymes for a desired amine product.

Lithium-Catalyzed anti-Markovnikov Intermolecular Hydroamination Reactions of Vinylarenes and Simple Secondary Amines

Various β-arylethylamine derivatives were straightforwardly obtained by the lithium-catalyzed anti-Markovnikov selective intermolecular hydroamination reaction of secondary aliphatic amines with vinylarenes. The use of only 1.5 mol % LiCH2TMS as a solid base in THF proved to be efficient to deliver the target products at room temperature with up to complete conversions. Both reaction partners were, moreover, used in equivalent amounts; thus, this protocol best respects the concepts of sustainable chemistry for the easy preparation of lead structures for pharmaceutically active compounds.

Rhodium-catalyzed highly regioselective hydroaminomethylation of styrenes with tetraphosphorus ligands

The highly linear-selective hydroaminomethylation of styrenes is very challenging. Herein, an efficient, highly chemoselective, and linear-selective hydroaminomethylation (l/b up to >99:1) of styrenes using Rh(nbd) 2SbF6 with a pyrrole-based 3,3′,5,5′- substituted tetraphosphorus ligand is documented. This is in sharp contrast to other available processes leading to branched amines and provides a novel atom economic approach to 3-arylpropylamines.

New Methods and Reagents in Organic Synthesis. 34. Diphenyl Phosphorazidate (DPPA) as a 1,3-Dipole. A Simple, Efficient Conversion of Alkyl Phenyl Ketones to 2-Phenylalkanoic Acids

Propiophenone (11) was conveniently converted to its enamines 12a-c using boron trifluoride etherate as a catalyst.Reaction of diphenyl phosphorazidate (DPPA) with the enamines 12a-c efficiently afforded the N-phosphorylated amidines 14a-c by the 1,3-dipolar cycloaddition of DPPA to the enamine double bond, followed by the evolution of nitrogen from the intermediate triazoline 13, and 1,2-migration of the phenyl group. 1,3-Dipolar elimination products 15a-c were also formed, though in very low yields.Some chemical properties of the N-phosphorylated amidine 14a, as well as the 1,3-dipolar character of DPPA, were investigated.By the same reaction sequences (enamine formation followed by the 1,3-dipolar cycloaddition of DPPA), some alkyl phenyl ketones 29a-c were conveniently converted to the N-phosphorylated amidines 31a, 31b, and 27 via the enamines 30a-c.However , in the case of acetophenone and its derivatives 33a-c, these reaction sequences proceeded sluggishly.Alkaline hydrolysis of the N-phosphorylated amidines 14a, 31a, 31b and 27 with potassium hydroxide afforded 2-phenylalkanoic acids 25 and 32a-c, respectively, in excellent yields.The overall three-step process of successive treatment of alkyl phenyl ketones (alkylmethyl) with pyrrolidine, DPPA, and potassium hydroxide may provide a new general method for the efficient conversion of alkyl aryl ketones to 2-arylalkanoic acids.Keywords - enamine; diphenyl phosphorazidate; boron trifluoride etherate; 1,3-dipolar cycloaddition; 1,2-migration; N-phosphorylated amidine; alkaline hydrolysis; alkyl aryl ketone; 2-arylalkanoic acid