Synthesis and reactivity of 7-azaindole (1H-pyrrolo[2,3-b]pyridine)

Crystal structure of 3-tert-butyl-3-hydroxy-1,3-dihydro-2H-pyrrolo[3,2-c]pyridin-2-one, C11H14N2O2

C11H14N2O2, orthorhombic, P212121 (no. 19), a = 7.5411(2) Å, b = 11.5148(2) Å, c = 12.5370(2) Å, V = 1088.64(4) Å3, Z = 4, R gt (F) = 0.0301, wR ref (F 2 ) = 0.0826, T = 296 K.

Discovery, characterization, and lead optimization of 7-azaindole non-nucleoside HIV-1 reverse transcriptase inhibitors

A library of 585 compounds built off a 7-azaindole core was evaluated for anti-HIV-1 activity, and ten hits emerged with submicromolar potency and therapeutic index >100. Of these, three were identified as non-nucleoside reverse transcriptase (RT) inhibitors and were assayed against relevant resistant mutants. Lead compound 8 inhibited RT with submicromolar potency (IC50=0.73μM) and also maintained some activity against the clinically important RT mutants K103N and Y181C (IC50=9.2, 3.5μM) in cell-free assays. Free energy perturbation guided lead optimization resulted in the development of a compound with a two-fold increase in potency against RT (IC50=0.36μM). These data highlight the discovery of a unique scaffold with the potential to move forward as next-generation anti-HIV-1 agents.

Mild one-pot Horner-Wadsworth-Emmons olefination and intramolecular N-arylation for the syntheses of indoles, all regio-isomeric azaindoles, and thienopyrroles

The syntheses of various N-protected aromatic-ring fused pyrrole-2-carboxylate derivatives have been accomplished using mild one-pot Horner-Wadsworth-Emmons olefination and Cu-catalyzed intramolecular N-arylation reactions. The optimized mild one-pot reaction conditions of various 2-bromo arylcarboxaldehydes with commercially available N-protected phosphonoglycine trimethylesters gave the desired aromatic-ring fused pyrrole-2-carboxylates, such as substituted indole-, all regio-isomeric azaindole-, and thienopyrrole-2-carboxylates, in good to excellent yields. These conditions showed broad substrate compatibility, without the loss of the protecting group.

Rhodium(iii)-catalyzed C–C coupling of 7-azaindoles with vinyl acetates and allyl acetates

The behaviour of electron-rich alkenes with 7-azaindoles in rhodium(iii)-catalyzed C–H activation is investigated.

A Copper-Based Metal-Organic Framework as an Efficient and Reusable Heterogeneous Catalyst for Ullmann and Goldberg Type C-N Coupling Reactions

A highly porous metal-organic framework (Cu-TDPAT), constructed from a paddle-wheel type dinuclear copper cluster and 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine (H₆TDPAT), has been tested in Ullmann and Goldberg type C-N coupling reactions of a wide range of primary and secondary amines with halobenzenes, affording the corresponding N-arylation compounds in moderate to excellent yields. The Cu-TDPAT catalyst could be easily separated from the reaction mixtures by simple filtration, and could be reused at least five times without any significant degradation in catalytic activity.

Homoleptic transition metal complexes of the 7-azaindolide ligand featuring κ(1)-N1 coordination

Homoleptic complexes of the anion of 7-azaindole (AzaIn) were synthesized and characterized for a series of 3d transition metals. For Mn(II), Fe(II), and Co(II), complexes of formula Na2[M(AzaIn)4]·2L (L = tetrahydrofuran (THF), 2-MeTHF, toluene, or benzene) were isolated by treatment of the corresponding metal chloride salts with 7-azaindole in the presence of sodium hexamethyldisilazide. The complexes adopt tetrahedral geometries with exclusive coordination to the transition metal ion through the pyrrolic N1 nitrogen atoms of the AzaIn ligands. Solid-state structures of the complexes demonstrate that the sodium cations remain tightly associated with the coordination entities through interaction with both the pyrrolic and pyridine nitrogen atoms of the azaindolide ligands. For Fe(II), replacement of the sodium cations by other alkali metal ions (Li or K) generates new complexes that demonstrate similar coordination geometries to the sodium salts. As a means of comparison, the Fe(II) complex of 4-azaindolide was also investigated. Na2[Fe(4-AzaIn)4]·2L adopts a similar solution structure to the 7-azaindolide complexes as judged by NMR spectroscopy and cyclic voltammetry. Density functional theory calculations were performed to investigate the bonding in the 7-azaindolide complexes. Results demonstrate that 7-azaindolide-κ(1)-N1 is a nearly pure sigma donor ligand that features a high degree of ionic character in its bonding to mid 3d transition metal ions.

Rhodium(III)-Catalyzed Oxidative Annulation of 7-Azaindoles and Alkynes via Double C-H Activation

Rhodium(III)-catalyzed double C-H activation involving N-directed ortho C-H activation and subsequent roll-over C-H activation of the heterocycle ring has been developed to form complex 7-azaindole derivatives in moderate to excellent yields. A broad scope of 7-azaindoles and internal alkynes has been demonstrated in this oxidative annulation reaction.

Suzuki-Miyaura cross-coupling of unprotected, nitrogen-rich heterocycles: substrate scope and mechanistic investigation

The Suzuki-Miyaura cross-coupling of unprotected, nitrogen-rich heterocycles using precatalysts P1 or P2 is reported. The procedure allows for the reaction of variously substituted indazole, benzimidazole, pyrazole, indole, oxindole, and azaindole halides under mild conditions in good to excellent yields. Additionally, the mechanism behind the inhibitory effect of unprotected azoles on Pd-catalyzed cross-coupling reactions is described based on evidence gained through experimental, crystallographic, and theoretical investigations.

Full functionalization of the 7-azaindole scaffold by selective metalation and sulfoxide/magnesium exchange

Filling positions: 7-Azaindoles are important targets in the pharmaceutical industry. All five carbon positions of the azaindole ring system can be functionalized in a predictable manner starting from the appropriately substituted azaindole 1 by directed metalation and halogen/magnesium and sulfoxide/magnesium exchange. The products are fully substituted azaindoles of type 2.

Fragment-based discovery of new highly substituted 1H-pyrrolo[2,3-b]- and 3H-imidazolo[4,5-b]-pyridines as focal adhesion kinase inhibitors

Focal adhesion kinase (FAK) is considered as an attractive target for oncology, and small-molecule inhibitors are reported to be in clinical testing. In a surface plasmon resonance (SPR)-mediated fragment screening campaign, we discovered bicyclic scaffolds like 1H-pyrazolo[3,4-d]pyrimidines binding to the hinge region of FAK. By an accelerated knowledge-based fragment growing approach, essential pharmacophores were added. The establishment of highly substituted unprecedented 1H-pyrrolo[2,3-b]pyridine derivatizations provided compounds with submicromolar cellular FAK inhibition potential. The combination of substituents on the bicyclic templates and the nature of the core structure itself have a significant impact on the compounds FAK selectivity. Structural analysis revealed that the appropriately substituted pyrrolo[2,3-b]pyridine induced a rare helical DFG-loop conformation. The discovered synthetic route to introduce three different substituents independently paves the way for versatile applications of the 7-azaindole core.