Development and Validation of Estimation of Genotoxic Impurity (Triethyl orthoformate content) in 5-methyl-4-isoxazole carboxylic acid (5-MIA) by using GC Technique

A simple, selective, precise and accurate Gas chromatographic method for determination of Triethyl orthoformate content (Genotoxic impurity) in 5-MIA is reported. The GC method development and validation as per the International Council for Harmonisation (ICH) guidelines Q2(R1). The effective chromatographic separations were achieved on DB-624, 60 m × 0.53 mm ID, with film thickness of 3.0 μm (Fused silica capillary column), Capillary injector temperature of 150°C, and Nitrogen Carrier gas. This method is unique as there is no UV response; hence GC Method was developed for Triethyl orthoformate. The elution was accomplished with the flow rate of 5.0 mL/min and Split Flow of 10 mL/minute. Detection was performed with FID detector (temp. 260°C) and with column oven temperature program. Methods range from limit of quantitation (LOQ) to 150% level with respect to specification concentration limit of impurity is linear and correlation coefficient of impurity is > 0.99. The linearity of Triethyl orthoformate covered from LOQ to 113 ppm (ie. LOQ to 150% of specification limit) and LOQ to 19 ppm wrt standard concentration. The limit of detection (LOD)values were observed were 2.5 ppm and limit of quantitation (LOQ) were 7.7 ppm, respectively. The parameters selected for the method validated were from international conference on harmonization guidelines, Indian pharmacopeia, USP. The percentage recovery from LOQ, 50% ,100% to 150% level of content were 87.70%, 98.60%, 102.25 and 96.59% respectively. The %RSD values were for LOQ to 150% were from 1.64%, 0.89%, 1.78 % and 1.49%. The range was covered from LOQ to 150% of standard concentration. The results of validation parameters were found in the acceptance range. Standard and sample were stable up to 30 h at when stored at room temperature. Also it was quite robust for the small change in method parameter like, change in column oven temperature(± 5 degree). Hence from the above parameter it was concluded that the GC method with FID detector is selective, precise, linear, and robust for simultaneous estimation of Triethyl orthoformate in Drug Substances.

Green synthesis of new lawsone enaminones and their Z/E(CC)-isomerization induced by organic solvent

The synthesis of a new class of lawsone enaminone derivatives by using lawsone, triethyl orthoformate and aromatic amines in the presence of guanidinium chloride under solvent-free conditions has been developed.

Investigation into the Properties of a Ruthenium(Polypyridyl)-NHC Compound.

The asymmetric imidazolium salt [Ru(dmbpy)2(bpip)](PF6)3 (bpip = 1-benzyl-3-isopropyl-1H-imidazo[4,5-f][1,10]phenanthrolinium), was prepared by a 4-step synthetic route. The isotopomer labelled with 13C at the C2 position of bpip was prepared from 1,10-phenanthroline-5,6-diamine and triethyl orthoformate-(formyl-13C). Deprotonation at low temperatures in acetonitrile using KOtBu and KHMDS were monitored by NMR to investigate the formation of the free N-heterocyclic carbene.

Three-Component Reaction of Diamines with Triethyl Orthoformate and Diethyl Phosphite and Anti-Proliferative and Antiosteoporotic Activities of the Products

A three-component reaction between diamines (diaminobenzenes, diaminocyclohexanes, and piperazines), triethyl orthoformate, and diethyl phosphite was studied in some detail. In the case of 1,3- and 1,4-diamines and piperazines, products of the substitution of two amino moieties—the corresponding tetraphosphonic acids—were obtained. In the cases of 1,2-diaminobenzene, 1,2-diaminocyclohexanes and 1,2-diaminocyclohexenes, only one amino group reacted. This is most likely the result of the formation of hydrogen bonding between the phosphonate oxygen and a hydrogen of the adjacent amino group, which caused a decrease in the reactivity of the amino group. Most of the obtained compounds inhibited the proliferation of RAW 264.7 macrophages, PC-3 human prostate cancer cells, and MCF-7 human breast cancer cells, with 1, trans-7, and 16 showing broad nonspecific activity, which makes these compounds especially interesting in the context of anti-osteolytic treatment and the blocking of interactions and mutual activation of osteoclasts and tumor metastatic cells. These compounds exhibit similar activity to zoledronic acid and higher activity than incadronic acid, which were used as controls. However, studies of sheep with induced osteoporosis carried out with compound trans-7 did not support this assumption.

Metal-free and solvent-free synthesis of m-terphenyls through tandem cyclocondensation of aryl methyl ketones with triethyl orthoformate

A facile metal-free and solvent-free benzannulation was developed for the construction of m-terphenyl derivatives starting from aryl methyl ketones and triethyl orthoformate. This is a tandem reaction which merged six steps into one-pot procedure.

Synthesis of New 2-Oxo-1,2-Dihydropyridine-3-Carboxylic Acid Derivatives

2,2-Dimethyl-5-((phenylamino)methylene)-1,3-dioxane-4,6-dione, prepared by the reaction of Meldrum’s acid with triethyl orthoformate and aniline, reacts with active methylene nitriles to afford 2-oxo-1,2-dihydropyridine-3-carboxylic acid derivatives, which are useful as drug precursors or perspective ligands.

Efficient synthesis, reactions and spectral characterization of pyrazolo[4’,3’:4,5]thieno[3,2-d] pyrimidines and related heterocycles

New pyrazolothienopyrimidines were synthesized. The key intermediate 4-aminothieno[2,3-c]pyrazole-5-carbonitrile 1 was converted to the chloroacetyl amino derivative 2 followed by nucleophilic substitution and Dimorth rearrangement upon treatment with nitrogen nucleophiles to give the pyrimidinones 3a-c. Treatment of 3a with formaldehyde and with triethyl orthoformate afforded the respective tetracyclic derivatives 4 and 5. Condensation of the amino group in the o-aminocarbonitrile 1 with triethyl orthoformate followed by cycloaddition reaction with hydrazine led to the formation of pyrazolothienopyrimidine 8. Compound 8 was used as a synthetic precursor to heterocyclic compounds comprised of pyrazole, triazole, triazine, and triazepine derivatives.