Padi Pratap Reddy

Application of [3 + 2]-Cycloaddition in the Synthesis of Valdecoxib

Abstract A large scale synthesis of valdecoxib 1 is described. Our work features potential application of [3 + 2]-dipolar cycloaddition involving enamine and in situ–generated nitrile oxide derivatives. GRAPHICAL ABSTRACT

Synthesis of Metabolites and Related Substances of Rabeprazole, an Anti-Ulcerative Drug

Abstract Rabeprazole sodium (Aciphex®) is a gastric proton pump inhibitor used for the prevention and treatment of gastric acid–related diseases. During the synthesis of bulk drug of rabeprazole sodium, we have observed metabolites rabeprazole sulfide and rabeprazole sulfone and related substances rabeprazole-N-oxide, rabeprazole sulfone-N-oxide, N-aralkyl rabeprazole, chloro rabeprazole, and methoxy rabeprazole as impurities in the drug substance. The present work describes the synthesis and characterization of these compounds.

Synthesis and Characterization of Metabolites and Potential Impurities of Lansoprazole, an Antiulcerative Drug

Abstract Lansoprazole (Prevacid) is an antiulcerative drug used for the treatment of duodenal and gastric ulcers, reflux oesophagitis, and Zollinger–Ellison syndrome. During the bulk synthesis of lansoprazole, we have observed five impurities: lansoprazole N-oxide, lansoprazole sulfone N-oxide, lansoprazole sulfide, lansoprazole sulfone and N-aralkyl lansoprazole. The present work describes the synthesis and characterization of these impurities.

Improved Synthesis of Irbesartan, an Antihypertensive Active Pharmaceutical Ingredient

Abstract An improved synthesis of the antihypertensive drug irbesartan, based on the Suzuki reaction, has been described.

Efficient Synthesis of Olmesartan Medoxomil, an Antihypertensive Drug

Abstract This document describes a simple and robust process for the synthesis of olmesartan medoxomil. This tailored process allows us to synthesize olmesartan medoxomil on a large scale with 50% overall yield. Also, our process has excellent control of the impurity profile in all the stages.

A NEW ENTRY TO ANTIHYPERTENSIVE ACTIVE PHARMACEUTICAL INGREDIENT, IRBESARTAN AND ITS ANALOGUES

A new synthesis of Irbesartan, an antihypertensive active pharmaceutical ingredient and its analogues is reported.

Novel Approach to the Synthesis of Omeprazole: An Antipeptic Ulcer Agent

A novel approach for the synthesis of omeprazole, a potent antiulcer drug, is described. The synthetic procedure involved the formation of an ester of the 5-methoxy thiobenzimidazole followed by coupling of the ester with the Grignard reagent of 2-chloromethyl-4-methoxy-3,5-dimethyl-pyridine.

New and Improved Synthesis of Montelukast, an Anti‐asthmatic Drug

Abstract A new industrially viable synthesis of Montelukast, an anti‐asthmatic drug, is described.

Alternative Synthesis of Tadalafil: PDE5 Inhibitor

Abstract Two-step alternative synthesis of tadalafil (1) is described. The synthesis features Pictet–Spengeler type reaction and DCC (N,N′-dicyclohexylcarbodiimide)/HOBt (N-hydroxybenzotriazole)–mediated double amidation employing sarcosine ethyl ester hydrochloride.

Impurity Profile Study of Venlafaxine Hydrochloride, an Antipsychotic Drug Substance

Venlafaxine hydrochloride is a phenyl ethylamine derivative, used for the treatment of depression. During the process development of venlafaxine hydrochloride, six process-related potential impurities were detected in high-performance liquid chromatography. All these impurities were identified, synthesized, and subsequently characterized by their respective spectral data (IR, mass, 1H NMR, and 13C NMR) as described in this article.