Discovery and gram-scale synthesis of BMS-593214, a potent, selective FVIIa inhibitor

Enantiodivergent kinetic resolution of 4-substituted 1,2,3,4-tetrahydroquinolines employing amine oxidase

Optically pure 1,2,3,4-tetrahydroquinolines (THQs) represent a class of important motifs in many natural products and pharmaceutical agents. While recent advances on redox biocatalysis have demonstrated the great potential of amine oxidases, all the transformations focused on 2-substituted THQs. The corresponding biocatalytic method for the preparation of chiral 4-substituted THQs is still challenging due to the poor activity and stereoselectivity of the available enzyme. Herein, we developed a biocatalytic kinetic resolution approach for enantiodivergent synthesis of 4-phenyl- or alkyl-substituted THQs. Through structure-guided protein engineering of cyclohexylamine oxidase derived from Brevibacterium oxidans IH-35 A (CHAO), the variant of CHAO (Y215H/Y214S) displayed improved specific activity toward model substrate 4-phenyl substituted THQ (0.14 U/mg, 13-fold higher than wild-type CHAO) with superior (R)-stereoselectivity (E > 200). Molecular dynamics simulations show that CHAO Y215H/Y214S allows a suitable substrate positioning in the expanded binding pocket to be facilely accessed, enabling enhanced activity and stereoselectivity. Furthermore, a series of 4-alkyl-substituted THQs can be transformed by CHAO Y215H/Y214S, affording R-isomers with good yields (up to 50 %) and excellent enantioselectivity (up to ee > 99 %). Interestingly, the monoamine oxidase from Pseudomonas fluorescens Pf0-1 (PfMAO1) with opposite enantioselectivity was also mined. Together, this system enriches the kinetic resolution methods for the synthesis of chiral THQs.

The Povarov Reaction: A Versatile Method to Synthesize Tetrahydroquinolines, Quinolines and Julolidines

The multicomponent Povarov reaction represents a powerful approach for the construction of substances containing N-heterocyclic frameworks. By using the Povarov reaction, in addition to accessing tetrahydroquinolines, quinolines and julolidines in a single step, it is possible to form the following new bonds: two Csp 3–Csp 3 and one Csp 3–Nsp 3, two Csp 2–Csp 2 and one Csp 2–Nsp 2, and four Csp 3–Csp 3 and two Csp 3–Nsp 1, respectively. This short review discusses the main features of the Povarov reaction, including its mechanism, the reaction scope by employing different catalysts and substrates, as well as stereoselective versions.

1 Introduction

2 Mechanism of the Povarov Reaction

3 Tetrahydroquinolines

4 Quinolines

5 Julolidines

6 Concluding Remarks

Pd-Catalyzed Nazarov-Type Cyclization: Application in the Total Synthesis of β-Diasarone and Other Complex Cyclopentanoids

We describe the palladium-catalyzed Nazarov-type cyclization of easily accessible (hetero)arylallyl acetates to pentannulated (hetero)arenes. This method provides ready access to various types of bi-, tri-, tetra-, and pentacyclic cyclopentanoids under neutral conditions. The synthetic utility is further demonstrated in the first total synthesis of β-diasarone and several other complex cyclopentanoids relevant to medicinal chemistry and materials science.

HSD1787, a Tetrahydro-3H-Pyrazolo[4,3-f]Quinoline Compound Synthesized via Povarov Reaction, Potently Inhibits Proliferation of Cancer Cell Lines at Nanomolar Concentrations

Multicomponent reaction (MCR) is often used to rapidly assemble complex compounds for drug screening. Povarov MCR has been used to prepare a new library containing tetrahydro-3H-pyrazolo[4,3-f]quinoline core and the library tested against MDA-MB-231 (a triple-negative breast cancer, TNBC, cell line). A few of the tetrahydro-3H-pyrazolo[4,3-f]quinoline-containing compounds, bearing 3-aminoindazolyl group, potently inhibited MDA-MB-231. The most active compound, HSD1787, was evaluated against NCI60 cell lines and this compound inhibited melanoma, renal, breast, ovarian, and leukemia cancer cell lines with GI₅₀ values as low as 0.1 μM. The tetrahydro-3H-pyrazolo[4,3-f]quinoline core is therefore a new scaffold that could be developed into potent anticancer therapeutics against difficult-to-treat cancers.

Progress in the Chemistry of Tetrahydroquinolines

Tetrahydroquinoline is one of the most important simple nitrogen heterocycles, being widespread in nature and present in a broad variety of pharmacologically active compounds. This Review summarizes the progress achieved in the chemistry of tetrahydroquinolines, with emphasis on their synthesis, during the period from mid-2010 to early 2018.

Catalyst-free and selective trifluoromethylative cyclization of acryloanilides using PhICF3Cl

Trifluoromethylative cyclization and biscyclization reactions of acryloanilides efficiently occurred under catalyst-free conditions.

Recent advances of the Povarov reaction in medicinal chemistry

The Povarov multicomponent reaction consists on the condensation of an aniline, an aldehyde, and an activated olefin to generate a tetrahydroquinoline adduct with 3 diversity points. Hereby, we report the main features of this transformation and its uses in medicinal chemistry. Relevant examples of the impact of Povarov adducts in different therapeutic areas are provided.

Synthesis and Spectroscopic Investigation of a Series of Push-Pull Boron Dipyrromethenes (BODIPYs)

A series of push-pull BODIPYs bearing multiple electron-donating and electron-acceptor groups were synthesized regioselectively from 2,3,5,6,8-pentachloro-BODIPY, and characterized by NMR spectroscopy, HRMS, and X-ray crystallography. The influence of the push-pull substituents on the spectroscopic and electrochemical properties of BODIPYs was investigated. Bathochromic shifts were observed for both absorbance (up to 37 nm) and emission (up to 60 nm) in different solvents upon introduction of the push-pull moieties. DFT calculations, consistent with the spectroscopic and cyclic voltammetry studies, show decreased HOMO-LUMO energy gaps upon the installation of the push-pull moieties. BODIPY 7 bearing thienyl groups on the 2 and 6 positions showed the largest λmax for both absorption (635-653 nm) and emission (706-707 nm), but also the lowest fluorescence quantum yields. All BODIPYs were nontoxic in the dark (IC50 > 200 μM) and showed low phototoxicity (IC50 > 100 μM, 1.5 J/cm2) toward human HEp2 cells. Despite the relatively low fluorescence quantum yields, the push-pull BODIPYS were effective for cell imaging, readily accumulating within cells and localizing mainly in the ER and Golgi. Our structure-property studies can guide future design of functionalized BODIPYs for various applications, including bioimaging and in dye-sensitized solar cells.

Kinetic Resolution of Benzylamines via Palladium(II)-Catalyzed C-H Cross-Coupling

A Pd(II)-catalyzed enantioselective C-H cross-coupling of benzylamines via kinetic resolution has been achieved using chiral mono-N-protected α-amino-O-methylhydroxamic acid (MPAHA) ligands. Both chiral benzylamines and ortho-arylated benzylamines are obtained in high enantiomeric purity. The use of a readily removable nosyl (Ns) protected amino group as the directing group is a crucial practical advantage. Moreover, the ortho-arylated benzylamine products could be further transformed into chiral 6-substituted 5,6-dihydrophenanthridines as important structural motifs in natural products and bioactive molecules.

Synthesis of hexahydrofuro[3,2-c]quinoline, a martinelline type analogue and investigation of its biological activity

Background

Candida susceptibility commonly occurs in breast cancer patients. Of which, Candida albicans is considered as a common pathogen causing candidiasis. Martinella iquitosensis (Bignoniaceae) is one of the species belonged to Martinella, distributed widely in Amazon basin. Its root extract yielded two complex substituted tetrahydroquinolines, Martinelline and Martinellic acid which were the first natural non-peptide bradykinin receptor antagonists identified.

Findings

In this study, a novel martinelline type analogue, named 2,3,3a,4,5,9b-hexahydro-8-phenoxy-4-(pyridin-2-yl)furo[3,2-c]quinoline, was synthesized and its preliminary anticancer activity and antifungal potential were investigated. This compound showed potential anticancer activity against MDAMB-231 breast cancer cells. Meanwhile it could enhance the fungistatic activity of miconazole against Candida albicans.

Conclusions

These findings provide an implication for the continue investigation and development of martinelline type analogues as therapeutic agents in the future.

Synthesis and spectroscopic properties of β,β'-dibenzo-3,5,8-triaryl-BODIPYs

A series of β,β'-bicyclo-3,5-diaryl-BODIPYs were synthesized from the corresponding β,β'-bicyclo-3,5-diiodo-BODIPYs (1a,b) via Pd(0)-mediated Suzuki cross-coupling reactions in 82-92% yields. Subsequent aromatization with DDQ afforded the corresponding β,β'-dibenzo-aryl-BODIPYs, which showed red-shifted absorptions and emissions in the near-IR range. The dibenzo-appended BODIPYs showed characteristic 1H-, 13C-, 11B- and 19F-NMR shifts, and nearly planar conformations by X-ray crystallography.

Structure-Based Design of Macrocyclic Coagulation Factor VIIa Inhibitors

On the basis of a crystal structure of a phenylpyrrolidine lead and subsequent molecular modeling results, we designed and synthesized a novel series of macrocyclic FVIIa inhibitors. The optimal 16-membered macrocycle was 60-fold more potent than an acyclic analog. Further potency optimization by incorporation of P1' alkyl sulfone and P2 methyl groups provided a macrocycle with TF/FVIIa Ki = 1.6 nM, excellent selectivity against a panel of seven serine proteases, and FVII-deficient prothrombin time EC2x = 1.2 μM. Discovery of this potent, selective macrocyclic scaffold opens new possibilities for the development of orally bioavailable FVIIa inhibitors.

Tissue factor-fVIIa inhibition: update on an unfinished quest for a novel oral antithrombotic

The tissue factor-coagulation factor VIIa complex (TF-fVIIa) is a well-validated biological target and has been the focus of extensive research directed toward the discovery of novel oral antithrombotics. This review briefly summarizes the key antithrombotic target validation data and provides an update on recent advances in small molecule TF-fVIIa inhibitors.