Jerry A. Murry

An efficient and scalable Ritter reaction for the synthesis of tert-butyl amides.

A scalable procedure for the conversion of nitriles to N-tert-butyl amides via the Ritter reaction was optimized employing tert-butyl acetate and acetic acid. The reaction has a broad scope for aromatic, alkyl, and alpha,beta-unsaturated nitriles.

Asymmetric synthesis of a potent, aminopiperidine-fused imidazopyridine dipeptidyl peptidase IV inhibitor.

A practical asymmetric synthesis of a novel aminopiperidine-fused imidazopyridine dipeptidyl peptidase IV (DPP-4) inhibitor 1 has been developed. Application of a unique three-component cascade coupling with chiral nitro diester 7, which is easily accessed via a highly enantioselective Michael addition of dimethyl malonate to a nitrostyrene, allows for the assembly of the functionalized piperidinone skeleton in one pot. Through a base-catalyzed, dynamic crystallization-driven process, the cis-piperidionone 16a is epimerized to the desired trans isomer 16b, which is directly crystallized from the crude reaction stream in high yield and purity. Isomerization of the allylamide 16b in the presence of RhCl(3) is achieved without any epimerization of the acid/base labile stereogenic center adjacent to the nitro group on the piperidinone ring, while the undesired enamine intermediate is consumed to <0.5% by utilizing a trace amount of HCl generated from RhCl(3). The amino lactam 4, obtained through hydrogenation and hydrolysis, is isolated as its crystalline pTSA salt from the reaction solution directly, as such intramolecular transamidation has been dramatically suppressed via kinetic control. Finally, a Cu(I) catalyzed coupling-cyclization allows for the formation of the tricyclic structure of the potent DPP-4 inhibitor 1. The synthesis, which is suitable for large scale preparation, is accomplished in 23% overall yield.

Practical synthesis of a highly functionalized thiazole ketone

Abstract Compound 1 is a uniquely substituted ketone prepared via addition of a thiazole anion to an aromatic nitrile in good overall yield. An exploration into the generality of the addition of thiazole anions to nitriles allowed us to make a variety of thiazole ketones in good to excellent yields. The non-odorous thiolate-mediated demethylation reaction used in the synthesis of 1 is also presented.

Practical routes toward the synthesis of 2-halo- and 2-alkylamino-4-pyridinecarboxaldehydes

Abstract We recently required an efficient synthesis of 2-halo- and 2-alkylamino-4-pyridinecarboxaldehydes. Several routes to these compounds were investigated resulting in efficient and practical procedures from readily available and inexpensive starting materials.

A practical preparation of 5-(ketoaryl)thiazoles

Abstract This article describes a facile synthesis of 2-substituted-5-(ketoaryl)thiazoles, which are important intermediates for the synthesis of biologically active compounds. A variety of 2-substituted thiazole anions were added to aryl nitriles to provide the desired ketones after aqueous hydrolysis.

Discovery of a stable molecular complex of an API with HCl: A long journey to a conventional salt

We report formation and characterization of the first pharmaceutically acceptable and stable molecular complex of a mono-HCl salt of Compound 1 with HCl. The novelty of this discovery is due to the fact that there is only one major basic site in the molecule. Thus this complex is reminiscent of other noncovalent crystalline forms including solvates, hydrates, cocrystals and others. To the best of our knowledge, the observed bis-HCl salt appears to be the first example of an active pharmaceutical ingredient in a form of a stable HCl complex. The paucity of stable complexes of APIs with HCl is likely due to the fact that HCl is a gas at ambient conditions and can easily evaporate compromising physical (and chemical) stability of a drug. The bis-HCl salt was chemically/physically stable at low humidity and the molecular HCl stays in the lattice until heated above 140 degrees C under nitrogen flow. Structure solution from powder diffraction using the Monte Carlo simulated annealing method as well as variable temperature ATR-FTIR suggest the possibility of weak hydrogen bonding between the molecular HCl and the nitrogen atom of the amide group. Two years later after the search for a suitable pharmaceutical salt began, the elusive conventional mono-HCl salt was obtained serendipitously concluding the lengthy quest for a regular salt. This work emphasizes the necessity to be open-minded during the salt selection process. It also highlights the difficult, lengthy and often serendipitous path of finding the most appropriate form of an API for pharmaceutical development.