Reductive amination plays a paramount role in pharmaceutical and medicinal chemistry owing to its synthetic merits and the ubiquitous presence of amines among biologically active compounds. It is one of the key approaches to C-N bond construction due to its operational easiness and a wide toolbox of protocols. Recent studies show that at least a quarter of C-N bond-forming reactions in the pharmaceutical industry are performed via reductive amination. This Review concisely compiles information on 71 medical substances that are synthesized by reductive amination. Compounds are grouped according to the principle of action, which includes drugs affecting the central nervous system, drugs affecting the cardiovascular system, anticancer drugs, antibiotics, antiviral and antifungal medicines, drugs affecting the urinary system, drugs affecting the respiratory system, antidiabetic medications, drugs affecting the gastrointestinal tract, and drugs regulating metabolic processes. A general synthetic scheme is provided for each compound, and the description is focused on reductive amination steps. The green chemistry metric of reaction mass efficiency was calculated for all reactions.

Reductive Amination in the Synthesis of Pharmaceuticals.

A specific combination, linked pro-drug or a compound of an angiotensin receptor antagonist and a NEPi are used in the treatment of hypertension.

Pharmaceutical combinations of an angiotensin receptor antagonist and an nep inhibitor

Single crystal structures of blockbuster antihypertensive drug Valsartan are revealed the first time in this report. Two new highly crystalline forms, named form E and an ethanol solvate form F, were discovered and fully characterized by PXRD, Raman, IR, TG, DSC, and DVS. Conformational flexibility and single crystal structures are discussed in detail. Physicochemical properties, such as hygroscopicity, chemical stability, crystallinity, and dissolution behaviors, are compared with the marketed solid-state form (amorphous state). The results show that the newly discovered highly crystalline form E presents a remarkably different dissolution behavior and superior chemical stability.

Highly Crystalline Forms of Valsartan with Superior Physicochemical Stability

The study is aimed at exploring the utility of thermoanalytical methods in the solid-state characterization of various crystalline forms of nevirapine. The different forms obtained by recrystallization of nevirapine from various solvents were identified using differential scanning calorimetry and thermogravimetric analysis (TGA). The appearance of desolvation peak accompanied by weight loss in TGA indicated the formation of solvates: hemi-ethanolate (Form I), hemi-acetonitrilate (Form II), hemi-chloroformate (Form III), hemi-THF solvate (Form IV), mixed hemi-ethanolate hemi-hydrate (Form V), and hemi-toluenate (Form VI). The higher desolvation temperatures of all the solvates except toluenate than their respective boiling point indicate tighter binding of solvent. Emphasis has been laid on the determination of heat capacity and heat of solution utilizing microreaction calorimeter to further distinguish the various forms. The enthalpy of solution (ΔHsol), an indirect measure of the lattice energy of a solid, was well correlated with the crystallinity of all the solid forms obtained. The magnitude of ΔHsol was found to be −14.14 kJ/mol for Form I and −2.83 kJ/mol for Form V in phosphate buffer of pH 2, exhibiting maximum ease of molecular release from the lattice in Form I. The heat capacity for solvation (ΔCp) was found to be positive, providing information about the state of solvent molecules in the host lattice. The solubility and dissolution rate of the forms were also found to be in agreement with their enthalpy of solution. Form (I), being the most exothermic, was found to be the most soluble of all the forms.

/pdf/solvated-crystalline-forms-of-nevirapine-thermoanalytical-3wxznmkanh.pdf

Solvated crystalline forms of nevirapine: thermoanalytical and spectroscopic studies.

The present invention belongs to the field of organic chemistry and refers to a process for the preparation of O -desmethylvenlafaxine (1-[2-Dimethylamino)-1-(4-hydroxyphenyl)ethyl]cyclohexanol) and its analogues. The invention also relates to a catalytic hydrogenation of cyano-group of the substituted acetonitrile.

Process for preparation of o-desmethylvenlafaxine and its analogue

A process for preparation of montelukast or a salt thereof is provided, the process including reacting a late intermediate compound which is 2-[1-[1-R-3-[2-(7 chloro quinolin-2-yl) vinyl [phenyl]-3-[2-methoxy carbonyl phenyl] propyl sulfonyl methyl] cyclo propyl] acetic acid or a salt thereof with methyl magnesium chloride or methyl magnesium bromide in an organic solvent. In one embodiment, the process includes reacting an earlier intermediate compound which is methyl 2-(3-R-(3-(2-(7-chloro 2-quinolinyl)-ethenyl)-3 hydroxy propyl) benzoate with methane sulfonyl chloride or toluene sulfonyl chloride to obtain a mesylated or tosylated derivative of the earlier intermediate compound; followed by a reaction of the mesylated or tosylated derivative with 1-mercapto methyl cyclopropane acetic acid in a polar solvent in a presence of a base to obtain the late intermediate compound.

Process for preparation of montelukast and its salts

The present invention relates to a method for the preparation of hydrates of 2-methyl-4-(4-methyl-1-piperazinyl)-10H-thieno [2,3-b] [1,5] benzodiazepine (hereinafter referred to as Olanzapine). The present invention also relates to a process for conversion of these hydrates into a pure crystalline form of olanzapine referred to as form-I. The present invention also relates to a method of converting Olanzapine Form-2 to Form-1.

Process for preparation of hydrates of olanzapine and their conversion into crystalline forms of olanzapine

The present invention relates to novel crystalline forms of (S)-N- (1-Carboxy-2­methyl-prop-1-yl) -N-pentanoyl-N- [2'-(1H-tetrazol-5-yl)- biphenyl-4-yl methyl amine (Valsartan) and to processes for their preparation Valsartan, chemically described as (S)-N- (1-Carboxy-2-methyl-prop-1-yl) -N-pentanoyl-N- [2'-(1H-tetrazol-5-yl)- biphenyl-4-yl methyl amine, is represented by the following structural formula (I)

Novel crystalline forms of (S)-N- (1-Carboxy-2-methyl-prop-1-yl) -N-pentanoyl-N- [2' -(1H-tetrazol-5-yl)- biphenyl-4-yl methyl] amine (Valsartan)

The present invention relates to novel anhydrous amorphous forms of [R-(E)-1-[[[l-[3-[2-[7-chloro-2-quinolinyl] ethenyl] phenyl]-3-[2-(1-hydroxy-l-methylethyl) phenyl] propyl] thio] methyl] cyclopropaneacetic acid alkali salts (Montelukast alkali salts) to processes for their preparation, to compositions containing them and to methods of treatment using the same. Montelukast is a leukotriene antagonist, is useful as anti-asthmatic, anti-allergic, anti-inflammatory and cytoprotective agent. Montelukast is represented by the formula (I).

Novel anhydrous amorphous forms of montelukast sodium salt

The present invention relates to an improved process for the preparation of phenethylamine derivatives or salts by hydrogenation of phenylacetonitriles in the presence of heterogeneous palladium on carbon catalyst.

Process for the preparation of phenethylamine derivative, an intermediate of Venlafaxine hydrochloride

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