Regioselective Synthesis of Fully Substituted Fused Pyrroles through an Oxidant-Free Multicomponent Reaction.

The synthesis of fully substituted fused pyrroles through a multicomponent reaction between a thioamide, an aldehyde, and ammonium acetate is described. This process improves on a route commonly employed in the patent literature by avoiding the use of potentially hazardous oxidants, which cause the formation of side products and require a stringent process of derisking to be utilized on scale. The reaction proceeds under mild conditions, displays excellent functional group tolerance, and facilitates diversification through multiple vectors.

Discovery of pyridyl urea sulfonamide inhibitors of NaV1.7.

NaV1.7 is an actively pursued, genetically validated, target for pain. Recently reported quinolinone sulfonamide inhibitors displayed promising selectivity profiles as well as efficacy in preclinical pain models; however, concerns about off-target liabilities associated with this series resulted in an effort to reduce the lipophilicity of these compounds. Successful prosecution of this strategy was challenging due to the opposing requirement for lipophilic inhibitors for NaV1.7 potency and in vivo clearance (CL). Deconstruction of the heterocyclic core of the quinolinone series and utilization of an intramolecular hydrogen bond to mimic the requisite pharmacophore enabled the introduction of polarity without adversely impacting CL. Ultimately, this strategy led to the identification of compound 29, which demonstrated favorable ADME and was efficacious in pre-clinical models of pain.

Discovery of a biarylamide series of potent, state-dependent NaV1.7 inhibitors.

The NaV1.7 ion channel has garnered considerable attention as a target for the treatment of pain. Herein we detail the discovery and structure-activity relationships of a novel series of biaryl amides. Optimization led to the identification of several state-dependent, potent and metabolically stable inhibitors which demonstrated promising levels of selectivity over NaV1.5 and good rat pharmacokinetics. Compound 18, which demonstrated preferential inhibition of a slow inactivated state of NaV1.7, was advanced into a rat formalin study where upon reaching unbound drug levels several fold over the rat NaV1.7 IC50 it failed to demonstrate a robust reduction in nociceptive behavior.

Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency, Pharmacokinetics, and Metabolic Properties to Obtain Atropisomeric Quinolinone (AM-0466) that Affords Robust in Vivo Activity.

Because of its strong genetic validation, NaV1.7 has attracted significant interest as a target for the treatment of pain. We have previously reported on a number of structurally distinct bicyclic heteroarylsulfonamides as NaV1.7 inhibitors that demonstrate high levels of selectivity over other NaV isoforms. Herein, we report the discovery and optimization of a series of atropisomeric quinolinone sulfonamide inhibitors [ Bicyclic sulfonamide compounds as sodium channel inhibitors and their preparation . WO 2014201206, 2014 ] of NaV1.7, which demonstrate nanomolar inhibition of NaV1.7 and exhibit high levels of selectivity over other sodium channel isoforms. After optimization of metabolic and pharmacokinetic properties, including PXR activation, CYP2C9 inhibition, and CYP3A4 TDI, several compounds were advanced into in vivo target engagement and efficacy models. When tested in mice, compound 39 (AM-0466) demonstrated robust pharmacodynamic activity in a NaV1.7-dependent model of histamine-induced pruritus (itch) and additionally in a capsaicin-induced nociception model of pain without any confounding effect in open-field activity.

Total syntheses of HMP-Y1, hibarimicinone, and HMP-P1.

Total syntheses of HMP-Y1, atrop-HMP-Y1, hibarimicinone, atrop-hibarimicinone, and HMP-P1 are described using a two-directional synthesis strategy. A novel benzyl fluoride Michael-Claisen reaction sequence was developed to construct the complete carbon skeleton of HMP-Y1 and atrop-HMP-Y1 via a symmetrical, two-directional, double annulation. Through efforts to convert HMP-Y1 derivatives to hibarimicinone and HMP-P1, a biomimetic mono-oxidation to desymmetrize protected HMP-Y1 was realized. A two-directional unsymmetrical double annulation and biomimetic etherification was developed to construct the polycyclic and highly oxidized skeleton of hibarimicinone, atrop-hibarimicinone, and HMP-P1. The use of a racemic biaryl precursor allowed for the synthesis of both hibarimicinone atropisomers and provides the first confirmation of the structure of atrop-hibarimicinone. Additionally, this work documents the first reported full characterization of atrop-hibarimicinone, HMP-Y1, atrop-HMP-Y1, and HMP-P1. Last, a pH-dependent rotational barrier about the C2-C2' bond of hibarimicinone was discovered, which provides valuable information necessary to achieve syntheses of the glycosylated congeners of hibarimicinone.

Gram-scale synthesis of the A'B'-subunit of angelmicin B.

A gram-scale enantiospecific synthesis of the A'B'-subunit of angelmicin B is reported. The synthesis involves a Lewis acid catalyzed contrasteric Diels-Alder reaction and a tandem silyl zincate 1,6-addition/enolate oxidation sequence.

Microwave-assisted Piloty-Robinson synthesis of 3,4-disubstituted pyrroles.

The synthesis of N-acyl 3,4-disubstituted pyrroles can be accomplished directly from hydrazine and an aldehyde via a Piloty-Robinson pyrrole synthesis. The use of microwave radiation for the cyclization and pyrrole formation greatly reduces the time necessary for this process and facilitates moderate to good yields from hydrazine for the corresponding 3,4-disubstituted products (5-12). By simple hydrolysis, the free N-H pyrroles can be accessed after the Piloty-Robinson reaction and then used directly in the synthesis of octaethylporphyrin (H2OEP, 14) and octaethyltetraphenylporphyrin (H2OETPP, 15).

Catalytic conjugate additions of carbonyl anions under neutral aqueous conditions.

The conjugate addition of carbonyl anions catalyzed by thiazolium salts that is fully operative under neutral aqueous conditions has been accomplished. The combination of alpha-keto carboxylates and thiazolium-derived zwitterions produces reactive carbonyl anions in a buffered protic environment that readily undergo conjugate additions to substituted alpha,beta-unsaturated 2-acyl imidazoles. The scope of the reaction has been examined and found to accommodate various alpha-keto carboxylates and beta-aryl substituted unsaturated 2-acyl imidazoles. The optimal precatalyst for this process is the commercially available thiazolium salt 5, a simple analogue of thiamin diphosphate. In this process, no benzoin products from carbonyl anion dimerization are observed. The corresponding 1,4-dicarbonyl compounds can be efficiently converted into esters and amides by way of activation of the N-methylimidazole ring via alkylation.

Efficient synthesis of acylsilanes using morpholine amides.

[reaction: see text] A general synthesis of acylsilanes from the corresponding morpholine amides and silyllithium species is described. The use of morpholine amides is economical and prevents over-addition by the silyl nucleophile. The procedure cleanly affords acylsilanes in good yields and circumvents the use of stoichiometric copper(I) cyanide typically employed to synthesize these compounds from acid chlorides.