Nga M. Do

A practical, efficient, and rapid method for the oxidation of electron deficient pyridines using trifluoroacetic anhydride and hydrogen peroxide–urea complex

Abstract A general method for the oxidation of electron-poor pyridines to their N-oxides using UHP and TFAA in either CH2Cl2 or CH3CN was developed. The methodology proved to tolerate a number of functional groups and substitution patterns and proceeded on notoriously difficult to oxidize substrates.

Application of Quantitative 19F and 1H NMR for Reaction Monitoring and In Situ Yield Determinations for an Early Stage Pharmaceutical Candidate

Quantitative NMR spectrometry (qNMR) is an attractive, viable alternative to traditional chromatographic techniques. It is a fast, easy, accurate, and nondestructive technique which allows an analyst to gain quantitative information about a component mixture without the necessity of authentic reference materials, as is the case with most other analytical techniques. This is ideal for the synthesis of active pharmaceutical ingredients (API) that are in the early stages of development where authentic standards of the analytes may not be available. In this paper, the application of (19)F and (1)H qNMR for reaction monitoring and in situ potency determinations will be discussed for an early stage pharmaceutical candidate with several analytical challenges. These challenges include low UV absorption, low ionization, thermal instability, and lack of authentic reference standards. Quantitative NMR provided quick, fit-for-purpose solutions for process development where conventional separation techniques were limited.

Method development and validation of arene substituted regioisomers in a pharmaceutical candidate by high temperature GC-FID.

This paper describes the development and validation of a high temperature gas chromatography flame ionization detection (HTGC-FID) method for the purity evaluation of arene substituted regioisomers in a key starting material of a pharmaceutical candidate in Phase 3 studies. The chromatographic conditions of the method employ a (5%-phenyl)-methylpolysiloxane packed column (30m×0.25mm) at a constant flow of 1.0mLmin(-1) with a gradient temperature program from 150°C to 400°C with injector and detector temperatures of 300°C and 340°C, respectively. The calibration curve for the desired product (r=0.9999) was assessed for five points in the range from approximately 1.0μgmL(-1) to 40μgmL(-1). The precision (% RSD) of the method was calculated for six replicate injections and found to be 0.81%. The limits of detection and quantitation were determined to be 0.06 and 0.20μgmL(-1), respectively.