Regioselective Deacetylation of Peracetylated Deoxy-C-glycopyranosides by Boron Trichloride (BCl3).

A general approach for regioselective deacetylation at sugar 3-OH of peracetylated 6-deoxy-C-glucopyranosides mediated by BCl3 was developed. The approach could be extended to other sugar-derived 6-deoxy-C-glycopyranosides, such as those derived from mannose, galactose, and rhamnose, with deacetylation occurring at varied sugar hydroxyl groups, and further extended to 4-deoxy-C-glucopyranosides with deacetylation occurring at sugar 3-OH. The approach would enable access to synthetically challenging carbohydrate derivatives. A possible mechanism of the regioselectivity was proposed.

Review of Voltage-gated Calcium Channel α2δ Subunit Ligands for the Treatment of Chronic Neuropathic Pain and Insight into Structure-activity Relationship (SAR) by Pharmacophore Modeling.

BACKGROUND: Neuropathic pain (NP) is a complex symptom related to nerve damage. The discovery of new drugs for treating chronic NP has been continuing for several decades, while more progress is still needed because of the unsatisfactory efficacy and the side effects of the currently available drugs. Among all the approved drugs for chronic NP, voltage- gated calcium channel (VGCC) α2δ subunit ligands, also known as gabapentinoids, are among the first-line treatment and represent a class of efficacious and relatively safe therapeutic agents. However, new strategies are still needed to be explored due to the unsatisfied response rate. OBJECTIVE: The aim of the study is to review the latest status of the discovery and development of gabapentinoids for the treatment of chronic NP by covering both the marketed and the preclinical/clinical ones. Moreover, it aims to analyze the structure-activity relationship (SAR) of gabapentinoids to facilitate the future design of structurally novel therapeutic agents targeting the VGCC α2δ subunit. METHODS: We searched PubMed Central, Embase, Cochrane Library, Web of Science, Scopus, and Espacenet for the literature and patents on diabetic peripheral neuropathic pain, postherpetic neuralgia, fibromyalgia, voltage-gated calcium channel α2δ subunit and related therapeutic agents from incipient to June 10, 2021. The SAR of gabapentinoids was analyzed by pharmacophore modeling using the Phase module in the Schrödinger suite. RESULTS: A variety of gabapentinoids were identified as VGCC α2δ ligands that have ever been under development to treat chronic NP. Among them, four gabapentinoids are marketed, one is in the active late clinical trials, and eight have been discontinued. Pharmacophore models were generated using the phase module in the Schrödinger suite, and common pharmacophores were predicted based on pharmacophoric features and analyzed. CONCLUSION: The latest progress in the discovery and development of gabapentinoids for the treatment of chronic NP was reviewed. Moreover, the structure-activity relationship (SAR) of gabapentinoids has been analyzed by pharmacophore modeling, which will be valuable for the future design of structurally novel therapeutic agents targeting the VGCC α2δ subunit.

Allosteric Inhibitors of SHP2: An Updated Patent Review (2015-2020).

Srchomology-2-domain-containing PTP 2 (SHP2) is a nonreceptor phosphatase encoded by the PTPN11 gene. Over expression of SHP2 is associated with various human diseases, such as Noonan syndrome, LEOPARD syndrome, and cancers. To overcome the shortcomings of existing orthosteric inhibitors, novel inhibitors targeting the allosteric site of SHP2 with high selectivity and low toxicity are under development. This paper reviews allosteric inhibitors of SHP2 published in patents from 2015 to 2020. The molecules are classified according to the chemical structure of the central core. SHP2 has long been considered as an 'undruggable' protein. Fortunately, a critical breakthrough was made by researchers from Novartis AG Ltd., who identified SHP099 as a highly potent, selective, soluble, and orally bioavailable SHP2 allosteric inhibitor. Currently, there are several allosteric inhibitors of SHP2 in clinical development. However, drug resistance is still a major challenge. The combination of SHP2 allosteric inhibitors and immunotherapy drugs or molecular targeted drugs is emerging as a promising therapeutic strategy against drug resistance.

Nickel-Catalyzed Amidoalkylation Reaction of γ-Hydroxy Lactams: An Access to 3-Substituted Isoindolinones.

An efficient Ni(ClO4)2·6H2O-promoted amidoalkylation reaction for the synthesis of 3-substituted isoindolinones involving various γ-hydroxy lactams and nucleophiles has been successfully developed. The transformation proceeds with both carbon (ketones and arenes) and heteroatom (alcohols, thiols, and amines) nucleophiles and in both intermolecular and intramolecular manners. The prominent features of the present strategy are wide substrate scope, excellent group tolerability, and moderate to good yields (up to 96% yield). The present strategy is also characterized by remarkable superiority over the current synthetic methods. Furthermore, the reaction could be scaled up to the multigram scale.

Release of Amino- or Carboxy-Containing Compounds Triggered by HOCl: Application for Imaging and Drug Design.

The overproduction of HOCl is highly correlated with diseases such as atherosclerosis, rheumatoid arthritis, and cancer. Whilst acting as a marker of these diseases, HOCl might also be used as an activator of prodrugs or drug delivery systems for the treatment of the corresponding disease. In this work, a new platform of HOCl probes has been developed that integrates detection, imaging, and therapeutic functions. The probes can detect HOCl, using both NIR emission and the naked eye in vitro, with high sensitivity and selectivity at ultralow concentrations (the detection limit is at the nanomolar level). Basal levels of HOCl can be imaged in HL-60 cells without special stimulation. Moreover, the probes provided by this platform can rapidly release either amino- or carboxy-containing compounds from prodrugs, during HOCl detection and imaging, to realize a therapeutic effect.

Synthesis, biological evaluation and 3D-QSAR studies of 1,2,4-triazole-5-substituted carboxylic acid bioisosteres as uric acid transporter 1 (URAT1) inhibitors for the treatment of hyperuricemia associated with gout.

As a part of our ongoing research to develop novel URAT1 inhibitors, 19 compounds (1a-1s) based on carboxylic acid bioisosteres were synthesized and tested for in vitro URAT1 inhibitor activity (IC50). The structure-activity relationship (SAR) exploration led to the discovery of a highly potent novel URAT1 inhibitor 1g, which was 225-fold more potent than the parent lesinurad in vitro (IC50 = 0.032 µM for 1g against human URAT1 vs 7.20 µM for lesinurad). Besides, 3D-QSAR pharmacophore models were established based on the activity of the compounds (1a-1s) by Accelrys Discovery Studio 2.5/HypoGen. The best hypothesis, Hypo 1, was validated by three methods (cost analysis, Fisher's randomization and leave-one-out). Although compound 1g is among the most potent URAT1 inhibitors currently under development in clinical trials, the Hypo1 appears to be favorable for future lead optimization.

Systematic Structure-Activity Relationship (SAR) Exploration of Diarylmethane Backbone and Discovery of A Highly Potent Novel Uric Acid Transporter 1 (URAT1) Inhibitor.

In order to systematically explore and better understand the structure-activity relationship (SAR) of a diarylmethane backbone in the design of potent uric acid transporter 1 (URAT1) inhibitors, 33 compounds (1a-1x and 1ha-1hi) were designed and synthesized, and their in vitro URAT1 inhibitory activities (IC50) were determined. The three-round systematic SAR exploration led to the discovery of a highly potent novel URAT1 inhibitor, 1h, which was 200- and 8-fold more potent than parent lesinurad and benzbromarone, respectively (IC50 = 0.035 µM against human URAT1 for 1h vs. 7.18 µM and 0.28 µM for lesinurad and benzbromarone, respectively). Compound 1h is the most potent URAT1 inhibitor discovered in our laboratories so far and also comparable to the most potent ones currently under development in clinical trials. The present study demonstrates that the diarylmethane backbone represents a very promising molecular scaffold for the design of potent URAT1 inhibitors.

Discovery of Flexible Naphthyltriazolylmethane-based Thioacetic Acids as Highly Active Uric Acid Transporter 1 (URAT1) Inhibitors for the Treatment of Hyperuricemia of Gout.

BACKGROUND: Gout is the most common inflammatory arthritis, which, if left untreated or inadequately treated, will lead to joint destruction, bone erosion and disability due to the crystal deposition. Uric acid transporter 1 (URAT1) was the promising therapeutic target for urate-lowering therapy. OBJECTIVE: The goal of this work is to understand the structure-activity relationship (SAR) of a potent lesinurad-based hit, sodium 2-((5-bromo-4-((4-cyclopropyl-naphth-1-yl)methyl)-4H-1,2,4-triazol-3- yl)thio)acetate (1c), and based on that discover a more potent URAT1 inhibitor. METHODS: The SAR of 1c was systematically explored and the in vitro URAT1 inhibitory activity of synthesized compounds 1a-1t was determined by the inhibition of URAT1-mediated [8-14C]uric acid uptake by human embryonic kidney 293 (HEK293) cells stably expressing human URAT1. RESULTS: Twenty compounds 1a-1t were synthesized. SAR analysis was performed. Two highly active URAT1 inhibitors, sodium 2-((5-bromo-4-((4-n-propylnaphth-1-yl)methyl)-4H-1,2,4-triazol-3- yl)thio)acetate (1j) and sodium 2-((5-bromo-4-((4-bromonaphth-1-yl)methyl)-4H-1,2,4-triazol-3- yl)thio)acetate (1m), were identified, which were 78- and 76-fold more active than parent lesinurad in in vitro URAT1 inhibitory assay, respectively (IC50 values for 1j and 1m were 0.092 µM and 0.094 µM, respectively, against human URAT1 vs 7.18 µM for lesinurad). CONCLUSION: Two highly active URAT1 inhibitors were discovered. The SAR exploration also identified more flexible naphthyltriazolylmethane as a novel molecular skeleton that will be valuable for the design of URAT1 inhibitors, as indicated by the observation that many of the synthesized naphthyltriazolylmethane- bearing derivatives (1b-1d, 1g, 1j and 1m) showed significantly improved UART1 inhibitory activity (sub-micromolar IC50 values) as compared with lesinurad which has the rigid naphthyltriazole skeleton.

Discovery of a Flexible Triazolylbutanoic Acid as a Highly Potent Uric Acid Transporter 1 (URAT1) Inhibitor.

In order to systematically explore and understand the structure-activity relationship (SAR) of a lesinurad-based hit (1c) derived from the replacement of the S atom in lesinurad with CH2, 18 compounds (1a-1r) were designed, synthesized and subjected to in vitro URAT1 inhibitory assay. The SAR exploration led to the discovery of a highly potent flexible URAT1 inhibitor, 1q, which was 31-fold more potent than parent lesinurad (IC50 = 0.23 µM against human URAT1 for 1q vs 7.18 µM for lesinurad). The present study discovered a flexible molecular scaffold, as represented by 1q, which might serve as a promising prototype scaffold for further development of potent URAT1 inhibitors, and also demonstrated that the S atom in lesinurad was not indispensable for its URAT1 inhibitory activity.

Design of SGLT2 Inhibitors for the Treatment of Type 2 Diabetes: A History Driven by Biology to Chemistry.

A brief history of the design of sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors is reviewed. The design of O-glucoside SGLT2 inhibitors by structural modification of phlorizin, a naturally occurring O-glucoside, in the early stage was a process mainly driven by biology with anticipation of improving SGLT2/SGLT1 selectivity and increasing metabolic stability. Discovery of dapagliflozin, a pioneering C-glucoside SGLT2 inhibitor developed by Bristol-Myers Squibb, represents an important milestone in this history. In the second stage, the design of C-glycoside SGLT2 inhibitors by modifications of the aglycone and glucose moiety of dapagliflozin, an original structural template for almost all C-glycoside SGLT2 inhibitors, was mainly driven by synthetic organic chemistry due to the challenge of designing dapagliflozin derivatives that are patentable, biologically active and synthetically accessible. Structure-activity relationships (SAR) of the SGLT2 inhibitors are also discussed.

Discovery of 6-deoxydapagliflozin as a highly potent sodium-dependent glucose cotransporter 2 (SGLT2) inhibitor for the treatment of type 2 diabetes.

Systematic mono-deoxylation of the four hydroxyl groups in the glucose moiety in dapagliflozin led to the discovery of 6-deoxydapagliflozin 1 as a more active sodium-dependent glucose cotransporter 2 (SGLT2) inhibitor (IC50 = 0.67 nM against human SGLT2 (hSGLT2) vs 1.16 nM for dapagliflozin). It exhibited more potent blood glucose inhibitory activity in rat oral glucose tolerance test and induced more urinary glucose in rat urinary glucose excretion test than its parent compound dapagliflozin.

1-(5-Bromo-2-chloro-phen-yl)-2,2-di-chloro-1-(4-eth-oxy-phen-yl)cyclo-propane.

The asymmetric unit of the title compound, C17H14BrCl3O, contains two independent mol-ecules with different dihedral angles between the benzene rings [79.2 (1) and 72.7 (1)°]. In the crystal, weak C-H⋯π inter-actions link mol-ecules related by translation along the b axis into two crystallographically independent chains.

The impact of click chemistry in medicinal chemistry.

INTRODUCTION: The copper(I)-catalyzed 1,3-dipolar cycloaddition of alkynes and azides to form 1,2,3-triazoles is the most popular reaction in click chemistry. This reaction is also near-perfect, in terms of its robustness, due to the high degree of reliability and complete specificity. Furthermore, this reaction has been used increasingly in drug discovery, because the formed 1,2,3-triazole can act as both a bioisostere and a linker. AREAS COVERED: This review provides an overview of a most important click reaction, 1,3-dipolar cycloadditions of alkynes and azides, in the drug discovery. EXPERT OPINION: Click chemistry is a very powerful tool, in the drug discovery, because it is very efficient in the creation of compound libraries through combinatorial methodology. However, the 1,2,3-triazole ring itself is not a commonly used pharmacophore and has rarely been found in marketed drugs, demonstrating that there are still some limitations during the use of 1,2,3-triazole in the molecules of drug candidates. Hopefully, in the next decade, we will witness the emergence of 1,2,3-triazole-bearing drugs on the market as this click reaction is used more and more widely in the drug discovery.

Synthesis and cytotoxic activity of novel 3-(1H-indol-3-yl)-1H-pyrazole-5-carbohydrazide derivatives.

A series of novel 3-(1H-indole-3-yl)-1H-pyrazole-5-carbohydrazide derivatives 4Ia-n, 4IIa-b and 6 were prepared by hydrazinolysis of ethyl 3-(1H-indole-3-yl)-1H-pyrazole-5-carboxylate with hydrazine hydrate in excellent yields. These new compounds were fully characterized by spectroscopic methods, and the important intermediates 3Ie, 3IIc and 3IId were further confirmed by X-ray crystallography. All the new compounds were evaluated for their cytotoxic activity against 4 human cancer cell lines by MTT method. Some of them exhibited more potent antiproliferative activity against HepG-2, BGC823 and BT474 cell lines than the positive drug 5-fluorourcail. Flow cytometry analysis showed that 4Ik and 4Il arrested the cell cycle at S phase.

5-(4-Ethoxy-benzyl)-1H-tetra-zole.

In the title mol-ecule, C(10)H(12)N(4)O, the tetra-zole and benzene rings form a dihedral angle of 67.52 (2)°. In the crystal, inter-molecular N-H⋯N hydrogen bonds link the mol-ecules into chains along the a axis. The relatively short distance of 3.760 (3) Šbetween the centroids of the tetra-zole rings suggests the existence of π-π inter-actions.

2-[(2,6-Dichloro-benz-yl)amino]-N-(4-methyl-thia-zol-2-yl)acetamide.

In the title compound, C(13)H(13)Cl(2)N(3)OS, the thia-zole and benzene rings are roughly parallel to one another in two layers [dihedral angle = 5.08 (2)°] because the N-C-C-N-C chain that links the two rings is folded [N-C-C-N torsion angle = 12.0 (2)°] rather than fully extended. An intra-molecular N-H⋯N inter-action occurs. In the crystal, weak inter-molecular N-H⋯N and C-H⋯O inter-actions are present and π-π inter-actions are indicated by the short distances [3.507 (3)-3.665 (2) Å] between the centroids of the thia-zole and benzene rings.

(3-Phenyl-isoxazol-5-yl)methanol.

In the title compound, C(10)H(9)NO(2), the isoxazole and phenyl rings form a dihedral angle of 25.82 (3)°. In the crystal, inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into ribbons propagating along [001]. The crystal packing is further stabilized by weak C-H⋯O and C-H⋯N inter-actions.

1-(3-tert-Butyl-4-hy-droxy-phen-yl)ethanone.

The title compound, C(12)H(16)O(2), is approximately planar (r.m.s. deviation = 0.030 Å), apart from two methyl groups of the tert-butyl unit [deviations of the C atoms = 1.140 (2) and -1.367 (1) Å]. In the crystal, inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into hexa-meric rings with R(6) (6)(48) graph-set motifs.

(5-Bromo-2-methyl-phen-yl)(4-eth-oxy-phen-yl)methanone.

In the title compound, C(16)H(15)BrO(2), the dihedral angle between the benzene rings is 68.5 (2)°. In the crystal structure, mol-ecules are linked by weak C-H⋯O hydrogen bonds into chains parallel to the b axis.

Ethyl 6-methyl-2-p-tolyl-pyrazolo[1,5-a]pyridine-5-carboxyl-ate.

In the title mol-ecule, C(18)H(18)N(2)O(2), the bicyclic ring system and the benzene ring form a dihedral angle of 13.45 (3)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds link mol-ecules into chains propagated along [201].