Danny Gauvreau

CRTH2 Antagonist MK-7246: A Synthetic Evolution from Discovery through Development

In this paper, we report the development of different synthetic routes to MK-7246 (1) designed by the Process Chemistry group. The syntheses were initially designed as an enabling tool for Medicinal Chemistry colleagues in order to rapidly explore structure-activity relationships (SAR) and to procure the first milligrams of diverse target molecules for in vitro evaluation. The initial aziridine opening/cyclodehydration strategy was also directly amenable to the first GMP deliveries of MK-7246 (1), streamlining the transition from milligram to kilogram-scale production needed to support early preclinical and clinical evaluation of this compound. Subsequently a more scalable and cost-effective manufacturing route to MK-7246 (1) was engineered. Highlights of the manufacturing route include an Ir-catalyzed intramolecular N-H insertion of sulfoxonium ylide 41 and conversion of ketone 32 to amine 31 in a single step with excellent enantioselectivity through a transaminase process. Reactions such as these illustrate the enabling impact and efficiency gains that innovative developments in chemo- and biocatalysis can have on the synthesis of pharmaceutically relevant target molecules.

A Practical Enantioselective Synthesis of Odanacatib, a Potent Cathepsin K Inhibitor, via Triflate Displacement of an α-Trifluoromethylbenzyl Triflate

An enantioselective synthesis of the Cathepsin K inhibitor odanacatib (MK-0822) 1 is described. The key step involves the novel stereospecific S(N)2 triflate displacement of a chiral alpha-trifluoromethylbenzyl triflate 9a with (S)-gamma-fluoroleucine ethyl ester 3 to generate the required alpha-trifluoromethylbenzyl amino stereocenter. The triflate displacement is achieved in high yield (95%) and minimal loss of stereochemistry. The overall synthesis of 1 is completed in 6 steps in 61% overall yield.

A Practical Synthesis of 5-Lipoxygenase Inhibitor MK-0633

Practical, chromatography-free syntheses of 5-lipoxygenase inhibitor MK-0633 p-toluenesulfonate (1) are described. The first route used an asymmetric zincate addition to ethyl 2,2,2-trifluoropyruvate followed by 1,3,4-oxadiazole formation and reductive amination as key steps. An improved second route features an inexpensive diastereomeric salt resolution of vinyl hydroxy-acid 22 followed by a robust end-game featuring a through-process hydrazide acylation/1,3,4-oxadiazole ring closure/salt formation sequence to afford MK-0633 p-toluenesulfonate (1).

Discovery of MK-1439, an orally bioavailable non-nucleoside reverse transcriptase inhibitor potent against a wide range of resistant mutant HIV viruses.

The optimization of a novel series of non-nucleoside reverse transcriptase inhibitors (NNRTI) led to the identification of pyridone 36. In cell cultures, this new NNRTI shows a superior potency profile against a range of wild type and clinically relevant, resistant mutant HIV viruses. The overall favorable preclinical pharmacokinetic profile of 36 led to the prediction of a once daily low dose regimen in human. NNRTI 36, now known as MK-1439, is currently in clinical development for the treatment of HIV infection.

Scalable Synthesis of a Prostaglandin EP4 Receptor Antagonist

The evolution of scalable, economically viable synthetic approaches to the potent and selective prostaglandin EP4 antagonist 1 is presented. The chromatography-free synthesis of multikilogram quantities of 1 using a seven-step sequence (six in the longest linear sequence) is described. This approach has been further modified in an effort to identify a long-term manufacturing route. Our final synthesis involves no step requiring cryogenic (< -25 degrees C) conditions; comprises a total of four steps, only three of which are in the longest linear synthesis; and features the use of two consecutive iron-catalyzed Friedel-Crafts substitutions.

Practical Synthesis of a Potent Bradykinin B1 Antagonist via Enantioselective Hydrogenation of a Pyridyl N-Acyl Enamide

A practical and efficient synthesis of bradykinin B(1) antagonist 1 is described. A convergent strategy was utilized which involved synthesis of three fragments: 3, 6, and 7. Cross coupling of fragments 6 and 7 followed by amidation with 3 enabled efficient synthesis of 1 in 19 steps total, a 35% overall yield from commercially available pyridine 10. The key to the success of the synthesis was the development of a fluorodenitration step to install the fluorine in pyridine 7 and a catalytic enantioselective hydrogenation of N-acyl enamide 9 to set the stereochemistry.

Novel oxazolidinone calcitonin gene-related peptide (CGRP) receptor antagonists for the acute treatment of migraine

In our efforts to develop CGRP receptor antagonists as backups to MK-3207, 2, we employed a scaffold hopping approach to identify a series of novel oxazolidinone-based compounds. The development of a structurally diverse, potent (20, cAMP+HS IC50=0.67 nM), and selective compound (hERG IC50=19 μM) with favorable rodent pharmacokinetics (F=100%, t1/2=7h) is described. Key to this development was identification of a 3-substituted spirotetrahydropyran ring that afforded a substantial gain in potency (10 to 35-fold).

Remote Electronic Control in the Regioselective Reduction of Succinimides: A Practical, Scalable Synthesis of EP4 Antagonist MF-310

A practical large-scale chromatography-free synthesis of EP4 antagonist MF-310, a potential new treatment for chronic inflammation, is presented. The synthetic route provided MF-310 as its sodium salt in 10 steps and 17% overall yield from commercially available pyridine dicarboxylate 7. The key features of this sequence include a unique regioselective reduction of succinimide 2 controlled by the electronic properties of a remote pyridine ring, preparation of cyclopropane carboxylic acid 3 via a Corey-Chaykovsky cyclopropanation, and a short synthesis of sulfonamide 5.

Practical Synthesis of a Renin Inhibitor via a Diastereoselective Dieckmann Cyclization

A scalable synthesis of a potent renin inhibitor (1) is described. The absolute stereochemistry is set via an unprecedented diastereoselective Dieckmann cyclization directed by a remote chiral protecting group. This transformation enables preparation of chiral 1,3-[3.3.1]-diazabicyclononenes by desymmetrization of alkyl-esters, with selectivities ranging from 4 to 17:1.