Hydroxylation of haloarenes is a fundamental transformation in synthetic organic chemistry. Hydroxypicolinamide ligands enable the efficient Cu-catalyzed hydroxylation of heteroaryl halides with a wide functional group tolerance. The Cu-MPBS system, originally designed for C–N coupling, enables the Cu-catalyzed hydroxylation of aryl bromides. A related derivative, Cu-HMPS, provides exceptional reactivity and purity for hydroxylation of aryl bromides, aryl iodides, and activated aryl chlorides. Ortho-activated substrates have shown exceptionally high reactivity and selectivity for Cu-catalyzed hydroxylation. More difficult aryl chlorides, substrates that require a higher activation temperature (120 °C), may be hydroxylated by the Cu-DMPS system that has superior intrinsic ligand stability. Reaction conditions may be tuned to target substrates through ligand, solvent, and base selection. Safe and robust processing conditions have been designed utilizing aqueous KOH, K2CO3, or K3PO4 in sulfolane or sulfolane and alcohol blends.

The melanocortin-4 receptor (MC4R) is a centrally expressed, class A GPCR that plays a key role in the regulation of appetite and food intake. Deficiencies in MC4R signaling result in hyperphagia and increased body mass in humans. Antagonism of MC4R signaling has the potential to mitigate decreased appetite and body weight loss in the setting of anorexia or cachexia due to underlying disease. Herein, we report on the identification of a series of orally bioavailable, small-molecule MC4R antagonists using a focused hit identification effort and the optimization of these antagonists to provide clinical candidate 23. Introduction of a spirocyclic conformational constraint allowed for simultaneous optimization of MC4R potency and ADME attributes while avoiding the production of hERG active metabolites observed in early series leads. Compound 23 is a potent and selective MC4R antagonist with robust efficacy in an aged rat model of cachexia and has progressed into clinical trials.

Biocatalytic reductive amination catalyzed by engineered imine reductase (RedAms) is a new and powerful tool for the synthesis of substituted chiral amines. Herein, we describe a streamlined synthesis of compound 3, a key intermediate to a CDK 2/4/6 inhibitor 1, relying on the enzymatic reductive amination of a hydroxyketone to introduce the chiral secondary amine with high diastereoselectivity. The improved synthesis of the hydroxyketone precursor by a titanium-catalyzed reductive cyclization and the process development for two SNAr reactions en route to 3 are also presented.

Radical fluoroalkylation is a powerful synthetic tool for the late-stage incorporation of fluorinated moieties into organic molecules, which is widely used in the development of pharmaceuticals and agrochemicals. Here, we report an efficient radical chlorodifluoromethylation protocol with sodium chlorodifluoromethanesulfinate, which is complementary to the existing late-stage difluoromethylation strategies. CF2Cl radical is a suitable surrogate for accessing the CF2H group while possessing completely different electronic properties compared to the CF2H radical. This method is chemoselective and regioselective for the chlorodifluoromethylation of (hetero)arenes and electron-rich alkenes and shows good functionality, tolerance, and generality on scope. The preparation of the sodium chlorodifluoromethanesulfinate is thoroughly investigated and can be scaled up to hundreds of kilograms. The method is successfully implemented on the synthesis of an oncology candidate compound 1.

A practical and efficient synthesis of α-heteroaryl propionic esters is developed by employing palladium-catalyzed α-heteroarylation of silyl ketene acetals, forming a wide variety of α-heteroaryl propionic esters with various substituents and functionalities in high yields. The success of this transformation is credited to the development of the bulky P,P═O ligand. The method has provided an efficient synthesis of α-heteroaryl propionic acids.

Manufacture of an EGFR inhibitor required the asymmetric synthesis of a key 3,4-trans-substituted pyrrolidine suitable for pilot-plant scale. The initial synthetic route utilized reagents and intermediates that posed safety concerns due to their energetic potential and then required supercritical fluid chromatography to access the desired single enantiomer. Burgess type reagents provide tremendous utility in organic synthesis but see limited use on large scales because of their high cost and instability. Nevertheless, extensive process development led to a scale-friendly process where in situ formation of a Boc-Burgess reagent enabled access to a chiral cyclic sulfamate from inexpensive materials. ReactIR monitoring was used to study intermediate stability and enabled processing on a multikilogram scale. The sulfamate was converted to trans-3-fluoro-4-aminopyrrolidine 1 with complete stereospecificity. Intermediate crystallinity offered purity control points where byproducts and impurities were rejected, avoiding the need for chromatography.

A family of 6-hydroxypicolinamide ligands have been identified as effective supporting ligands for Cu-catalyzed couplings of heteroaryl bromides and chlorides with heteroaryl primary amines. The C–N couplings are carried out at 80–120°C in DMSO or sulfolane using K2CO3 or K3PO4 as the base with 2–10 mol % CuI and supporting ligand. The strength of the base was found to have an impact on the chemoselectivity and rate. The use of K2CO3 as the base enabled selective C–N coupling of aryl bromides over aryl chlorides with 2–5 mol % Cu at 80–120 °C. With K3PO4 as the base, aryl chlorides are capable of undergoing C–N coupling, though 5–10 mol % Cu is required at 120–130 °C. Members of the ligand family are straightforward to prepare in one step from 6-hydroxypicolinic acid and the corresponding anilines.

Indole acids 1, 2, and 3 are potent 5′-adenosine monophosphate-activated protein kinase (AMPK) activators for the potential treatment of diabetic nephropathy. Compounds 1–3 were scaled to supply material for preclinical studies, and indole 3 was selected for advancement to first-in-human clinical trials and scaled to kilogram quantities. The progression of the synthesis strategy for these AMPK activators is described, as routes were selected for efficient structure–activity relationship generation and then improved for larger scales. The developed sequences employed practical isolations of intermediates and APIs, reproducible cross-coupling, hydrolysis, and other transformations, and enhanced safety and purity profiles and led to the production of 40–50 g of 1 and 2 and 2.4 kg of 3. Multiple polymorphs of 3 were observed, and conditions for the reproducible formation of crystalline material suitable for clinical development were identified.

A potent 5-HT4 partial agonist, 1 (PF-04995274), targeted for the treatment of Alzheimer's disease and cognitive impairment, has been prepared on a multi-kilogram scale. The initial synthetic route, that proceeded through a 4-substituted 3-hydroxybenzisoxazole core, gave an undesired benzoxazolinone through a Lossen-type rearrangement. Route scouting led to two new robust routes to the desired 4-substituted core. Process development led to the efficient assembly of the API on a pilot plant scale under process-friendly conditions with enhanced throughput. In addition, crystallization of a hemicitrate salt of the API with pharmaceutically beneficial properties was developed to enable progression of clinical studies.

Myeloperoxidase (MPO) is a heme peroxidase that catalyzes the production of hypochlorous acid. Clinical evidence suggests a causal role for MPO in various autoimmune and inflammatory disorders including vasculitis and cardiovascular and Parkinson's diseases, implying that MPO inhibitors may represent a therapeutic treatment option. Herein, we present the design, synthesis, and preclinical evaluation of N1-substituted-6-arylthiouracils as potent and selective inhibitors of MPO. Inhibition proceeded in a time-dependent manner by a covalent, irreversible mechanism, which was dependent upon MPO catalysis, consistent with mechanism-based inactivation. N1-Substituted-6-arylthiouracils exhibited low partition ratios and high selectivity for MPO over thyroid peroxidase and cytochrome P450 isoforms. N1-Substituted-6-arylthiouracils also demonstrated inhibition of MPO activity in lipopolysaccharide-stimulated human whole blood. Robust inhibition of plasma MPO activity was demonstrated with the lead compound 2-(6-(5-chloro-2-methoxyphenyl)-4-oxo-2-thioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (PF-06282999, 8) upon oral administration to lipopolysaccharide-treated cynomolgus monkeys. On the basis of its pharmacological and pharmacokinetic profile, PF-06282999 has been advanced to first-in-human pharmacokinetic and safety studies.

Process development and the multikilogram synthesis of a novel azetidinyl ketolide antibiotic is described. Starting with clarithromycin, the eight-step synthesis features several telescoped operations and direct isolations, which results in a significant improvement in throughput and a major reduction in solvent usage and waste stream volume over the first scale-up campaign. Particular highlights of this effort include the development of an efficient synthesis of 3-hydroxy-1,5-naphthyridine-4-carbaldehyde via a Skraup process and engineering a robust final API synthesis. We also discovered a crystalline monotosylate salt that addressed significant formulation and degradation issues experienced when using the noncrystalline freebase.

A scalable synthesis of CE-157119 HCl salt (1), an SRI/5-HT2A antagonist, was developed via the regioselective SNAr etherification between a phenol and an N-methylamide. This early development route shortened the original 5-step synthesis to three steps, eliminated all chromatography and increased the overall yield from 15% to 34%. The process was implemented for API manufacture from 100-g scale to multikilogram scale.

N-Aryl pyrazoles were prepared from anilines in a three step telescoped approach. An aniline was diazotized to give the diazonium fluoroborate, followed by reduction with tin(II) chloride to give the corresponding hydrazine, which in turn reacted with a ketoenamine to give the N-aryl pyrazole. The deprotection of the methyl ether was accomplished with PhBCl2 to give the final product. The continuous flow methodology was used to minimize accumulation of the highly energetic and potentially explosive diazonium salt and hydrazine intermediates to enable the safe scale-up of N-aryl pyrazoles. The heterogeneous reaction mixture was successfully handled in both lab scale and production scale. A continuous extraction was employed to remove organic impurities from the diazotization step, which eliminated the need for chromatography in the purification of the final N-aryl pyrazole.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The tricyclic bisamidines L1 and L2 are designed to be preconstrained so as to present synperiplanar donor sites for metal coordination. Their very different bite angles of 35° and 70° result from the incorporation of two five-membered instead of six-membered rings in their respective backbones. Distinct coordination preferences in a variety of metal complexes have now been confirmed by X-ray structural studies. While L1 afforded monodentate, symmetrical and unsymmetrical chelating as well as bimetallic bridging modes in its complexes, L2 has been found exclusively in a bidentate chelating mode.

A scaleable synthesis of 3-hydroxy-1,5-naphthyridine-4-carbaldehyde is described. 3-Amino-5-methoxy-4-methyl-pyridine underwent the Skraup reaction to give the corresponding 1,5-naphthyridine which, upon treatment with DMF-DMA in the presence of catalytic amount of LiOH, provided the N,N-dimethyl enamine intermediate. Oxidative cleavage, followed by removal of the methyl ether afforded the titled product.