Palladium-catalyzed sulfonylative coupling of benzyl(allyl) carbonates with arylsulfonyl hydrazides

Molybdenum Complex-Catalyzed N-Alkylation of Bulky Primary and Secondary Amines

Aliphatic allylic amines are present in a large number of complex and pharmaceutically relevant molecules. The direct amination of allylic electrophiles serves as the most common method toward the preparation of these motifs. However, the use of feedstock reaction components (allyl alcohol and aliphatic amine) in these transformations remains a great challenge. Such a challenge primarily stems from the high Lewis basicity and large steric hindrance of aliphatic amines, in addition to the low reactivity of allylic alcohols. Herein, we report a general solution to these challenges. The developed protocol allows an efficient allylic amination of allyl alcohols with sterically bulky aliphatic amines in the presence of an inexpensive earth-abundant molybdenum complex. This simple and economic protocol also enables regioselective branched amination; the practicality of the reaction was shown in an efficient, scaled-up synthesis of several drugs.

Expanding the Solvent/Protein Region Occupation of the Non-Nucleoside Reverse Transcriptase Inhibitor Binding Pocket for Improved Broad-Spectrum Anti-HIV-1 Efficacy: from Rigid Phenyl-Diarylpyrimidines to Flexible Hydrophilic Piperidine-Diarylpyrimidines

Considering the nonideal antiresistance efficacy of our previously reported non-nucleoside reverse transcriptase inhibitor 7, a series of novel piperidine-diarylpyrimidine derivatives were designed through expanding solvent/protein region occupation. The representative compound 15f proved to be exceptionally potent against Y188L (EC50 = 23 nM), F227L + V106A (EC50 = 15 nM) and RES056 (EC50 = 45 nM), significantly better than 7. This analog exerted strong inhibition against wild-type HIV-1 (EC50 = 3 nM) and single mutant strains (L100I, K103N, Y181C, E138 K). Notably, its cytotoxicity and selectivity (CC50 = 18.23 μM, SI = 6537) were 4-fold better than etravirine and rilpivirine. Additionally, it exhibited minimal suppression of CYP isoenzymes and hERG, indicating low potential for drug-drug interactions and cardiotoxicity. No significant acute toxicity and tissue damage at a dose of 2 g/kg were revealed. These findings lay the groundwork for the advancement of 15f as a highly potent, safe, and broad-spectrum NNRTI for HIV therapy.

Fragment Addition-Based Design of Heteroaromatic-Biphenyl-DAPYs as Potent and Orally Available Non-nucleoside Reverse Transcriptase Inhibitors Featuring Significantly Enhanced Safety

Our previously disclosed biphenyl-DAPY 3 emerged as a potent inhibitor against WT HIV-1 and various mutant strains. Yet, its journey toward clinical application was thwarted by pronounced cytotoxicity and low selectivity (CC50 = 6 μM, SI = 3515). The safety improvement approach we employed in this work entailed the incorporation of diverse heteroaromatic substituents at the C5 position to exploit the tolerant regions of the NNRTIs' binding pocket through fragment addition-based drug design strategy, ultimately leading to the identification of a series of novel heteroaromatic-biphenyl-DAPYs. The exemplary compound 10d revealed a striking reduction in cytotoxicity (CC50 > 272.81 μM), nearly 45.5 times lower than 3, while showcasing 15-fold increase in selectivity (SI > 52632). This analog sustained exceptional anti-HIV-1 activity against both WT HIV-1 (EC50 = 5 nM) and various mutant strains. Compared to 3, a markedly slower rate of metabolism in human liver microsomes of 10d was observed. Its pharmacokinetic profile was equally captivating, featuring excellent oral bioavailability (F = 57.4%). Moreover, 10d exhibited a delicate sensitivity toward CYP, minimal inhibition of hERG, and no detectable acute toxicity in vivo. These enchanting findings illuminated the potential of 10d as a promising candidate for HIV-1 therapy.

Palladium-Catalyzed Tsuji-Trost-Type Reaction of 3-Indolylmethylacetates with O, and S Soft Nucleophiles

The chemical valorization of widespread molecules in renewable sources is a field of research widely investigated in the last decades. In this context, we envisaged that indole-3-carbinol, present in different Cruciferae plants, could be a readily available building block for the synthesis of various classes of indoles through a palladium-catalyzed Tsuji-Trost-type reaction with O and S soft nucleophiles. The regiochemical outcome of this high-yielding functionalization shows that the nucleophilic substitution occurs only at the benzylic position. Interestingly, with this protocol, the sulfonyl unit could be appended to the indole nucleus, providing convenient access to new classes of molecules with potential bioactivity.

Neutral nickel-catalyzed dehydrosulfonylation of unactivated allylic alcohols under mild conditions

Allyl sulfones are important sulfur-containing compounds that have widespread applications in organic synthesis, medicinal chemistry and materials science. Herein, nickel-catalysed dehydrosulfonylation of unactivated allyl alcohols with aryl sulfonyl hydrazides without additional active agents under mild conditions was developed. A variety of functional allyl sulfones could be efficiently synthesized in the presence of air-stable Ni(acac)2 as the catalyst and 1,1'-bis(diphenylphosphino)ferrocene (DPPF) as the ligand.

Synthetic approaches and application of clinically approved small-molecule Anti-HIV drugs: An update

Application of chemotherapeutic agents to inhibit the HIV replication process has brought about a significant metamorphosis in the landscape of AIDS. Substantial declines in morbidity and mortality rates have been attained, accompanied by notable decreases in healthcare resource utilization. However, treatment modalities do not uniformly inhibit HIV replication in every patient, while the emergence of drug-resistant viral strains poses a substantial obstacle to subsequent therapeutic interventions. Furthermore, chronic administration of therapy may lead to the manifestation of toxicities. These challenges necessitate the exploration of novel pharmacological agents and innovative therapeutic approaches aimed at effectively managing the persistent viral replication characteristic of chronic infection. This review examines the role of clinically approved small-molecule drugs in the treatment of HIV/AIDS, which provides an in-depth analysis of the major classes of small-molecule drugs, including nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), integrase inhibitors, entry inhibitors, and pharmacokinetic enhancers. The review mainly discusses the application, synthetic routes, and mechanisms of action of small-molecule drugs employed in the treatment of HIV, as well as their use in combination with antiretroviral therapy, presenting viewpoints on forthcoming avenues in the development of novel anti-HIV drugs.

Glyoxylic Acid Monohydrate-Promoted Formation of the C-SO2 Bond Starting from Maleimides/Quinones and Sodium Sulfinates

By using glyoxylic acid monohydrate as a promoter, a wide range of substances containing a C-SO2 bond could be obtained from N-substituted maleimides or quinones and sodium sulfinates. The protocol features mild reaction conditions, short reaction time, and good atomic economics, which provides an alternative protocol for the α-sulfonylation of α,β-unsaturated ketones.

Rhodium-Catalyzed Regio- and Enantioselective Allylic Sulfonylation from Sulfonyl Hydrazides

A highly regio- and enantioselective allylic sulfonylation has been developed with rhodium and bisoxazolinephosphine (NPN*) ligands from racemic branched allylic carbonates and readily available sulfonyl hydrazides under neutral conditions. Branch-selective allylic sulfones with a >20:1 branch:linear ratio and >99% ee could be synthesized in ≤96% yield. Both Z and E linear allylic carbonates could also be converted into the same chiral branched allylic sulfones with high regio- and enantioselectivities.

Fragment Hopping-Based Design of Novel Biphenyl-DAPY Derivatives as Potent Non-Nucleoside Reverse Transcriptase Inhibitors Featuring Significantly Improved Anti-Resistance Efficacy

To enhance the anti-resistance efficacy of our previously reported non-nucleoside reverse transcriptase inhibitor (NNRTI) 4, a series of novel biphenyl-DAPY derivatives were developed using the fragment-hopping strategy. Most of the compounds 8a-v exhibited remarkably improved anti-HIV-1 potency. The most active compound 8r proved to be exceptionally potent against the wild-type HIV-1 (EC₅₀ = 2.3 nM) and five mutant strains, such as K103N (EC₅₀ = 8 nM) and E138K (EC₅₀ = 6 nM), significantly better than 4. The new DAPY analogue was 8-fold less cytotoxic and had a 17-fold higher selectivity index (CC₅₀ = 40.77 μM, SI > 17391) than etravirine and rilpivirine. Also, it displayed favorable pharmacokinetic properties with an oral bioavailability of 31.19% and weak sensitivity toward both CYP and hERG. No apparent acute toxicity (2 g/kg) and tissue damage occurred. These findings will further expand the possibility of successfully identifying biphenyl-DAPY analogues as highly potent, safe, and orally active NNRTIs for HIV treatment.

Multicomponent Sulfonylation of Alkenes to Access β-Substituted Arylsulfones

A novel multicomponent sulfonylation of alkenes is described for the assembly of various β-substituted arylsulfones using cheap and easily available K₂S₂O₅ as a sulfur dioxide source. Of note, the procedure does not need any extra oxidants and metal catalysts and exhibits a relatively wide substrate scope and good functional group compatibility. Mechanistically, an initial arylsulfonyl radical is formed involving the insertion of sulfur dioxide with aryl diazonium salt, followed by alkoxyarylsulfonylation or hydroxysulfonylation of alkenes.

Picomolar inhibitor of reverse transcriptase featuring significantly improved metabolic stability

Considering the undesirable metabolic stability of our recently identified NNRTI 5 (t_1/2 = 96 min) in human liver microsomes, we directed our efforts to improve its metabolic stability by introducing a new favorable hydroxymethyl side chain to the C-5 position of pyrimidine. This strategy provided a series of novel methylol-biphenyl-diarylpyrimidines with excellent anti-HIV-1 activity. The best compound 9g was endowed with remarkably improved metabolic stability in human liver microsomes (t_1/2 = 2754 min), which was about 29-fold longer than that of 5 (t_1/2 = 96 min). This compound conferred picomolar inhibition of WT HIV-1 (EC₅₀ = 0.9 nmol/L) and low nanomolar activity against five clinically drug-resistant mutant strains. It maintained particularly low cytotoxicity (CC₅₀ = 264 μmol/L) and good selectivity (SI = 256,438). Molecular docking studies revealed that compound 9g exhibited a more stable conformation than 5 due to the newly constructed hydrogen bond of the hydroxymethyl group with E138. Also, compound 9g was characterized by good safety profiles. It displayed no apparent inhibition of CYP enzymes and hERG. The acute toxicity assay did not cause death and pathological damage in mice at a single dose of 2 g/kg. These findings paved the way for the discovery and development of new-generation anti-HIV-1 drugs.

Ni-catalyzed C-S bond construction and cleavage

Sulfur-containing compounds have attracted considerable interest due to their wide-ranging applications in pharmaceuticals, agriculture, natural products, and organic materials. The development of efficient and rapid methods for the construction and transformation of sulfur-containing compounds is of great importance. Since nickel is inexpensive and has a variety of valence states, strong nucleophilicity and low energy barriers for oxidative addition, the construction and transformation of sulfur-containing compounds by nickel-catalyzed cross-coupling have become important strategies. In addition, sulfur-containing compounds have also been playing increasingly important roles in the field of cross-coupling due to their thermodynamically stable but dynamic activity. This review will focus on nickel-catalyzed construction and transformation of various sulfide-containing compounds, such as sulfides, disulfides, and hypervalent sulfur-containing compounds.

Development of fluorine-substituted NH2-biphenyl-diarylpyrimidines as highly potent non-nucleoside reverse transcriptase inhibitors: Boosting the safety and metabolic stability

Our recent studies for nonnucleoside reverse transcriptase inhibitors identified a highly potent compound JK-4b against WT HIV-1 (EC₅₀ = 1.0 nmol/L), but the poor metabolic stability in human liver microsomes (t _1/2 = 14.6 min) and insufficient selectivity (SI = 2059) with high cytotoxicity (CC₅₀ = 2.08 μmol/L) remained major issues associated with JK-4b. The present efforts were devoted to the introduction of fluorine into the biphenyl ring of JK-4b, leading to the discovery of a novel series of fluorine-substituted NH₂-biphenyl-diarylpyrimidines with noticeable inhibitory activity toward WT HIV-1 strain (EC₅₀ = 1.8-349 nmol/L). The best compound 5t in this collection (EC₅₀ = 1.8 nmol/L, CC₅₀ = 117 μmol/L) was 32-fold in selectivity (SI = 66,443) compared to JK-4b and showed remarkable potency toward clinically multiple mutant strains, such as L100I, K103N, E138K, and Y181C. The metabolic stability of 5t was also significantly improved (t _1/2 = 74.52 min), approximately 5-fold higher than JK-4b in human liver microsomes (t _1/2 = 14.6 min). Also, 5t possessed good stability in both human and monkey plasma. No significant in vitro inhibition effect toward CYP enzyme and hERG was observed. The single-dose acute toxicity test did not induce mice death or obvious pathological damage. These findings pave the way for further development of 5t as a drug candidate.

Structure-Based Discovery of Novel NH2-Biphenyl-Diarylpyrimidines as Potent Non-Nucleoside Reverse Transcriptase Inhibitors with Significantly Improved Safety: From NH2-Naphthyl-Diarylpyrimidine to NH2-Biphenyl-Diarylpyrimidine

Results from recently completed studies suggested that the NH₂-naphthyl-diarylpyrimidine JX-7 displayed remarkable inhibitory activity against wild-type HIV-1 (EC₅₀ = 5 nM) and numerous clinically observed variants in MT-4 cells; however, its high cytotoxicity (CC₅₀ = 19 μM) precluded its further development as a clinical candidate. One approach we took to improve the safety involved replacing the naphthyl of JX-7 with biphenyl to provide a series of novel NH₂-biphenyl-DAPYs. Investigation of the structure-activity relationships (SARs) led to the identification of 4ab, a potent NNRTI with significantly reduced cytotoxicity (CC₅₀ = 120 μM), approximately 6-fold lower than JX-7, which maintained remarkable anti-HIV-1 activity against wild-type HIV-1 (EC₅₀ = 1.9 nM) and multiple mutant strains simultaneously. Also, 4ab displayed weak CYP sensitivity, little inhibition of hERG, and no apparent in vivo acute toxicity. These promising results demonstrate that 4ab can be used as a drug candidate for HIV-1 therapy.

Base-promoted synthesis of diarylsulfones from sulfonyl hydrazines and diaryliodonium salts

An efficient and concise method for the synthesis of diverse substituted sulfones was developed with high selectivity. Using n-PrOH as the solvent, diaryl sulfones are formed even on a gram scale via metal-free coupling from sulfonyl hydrazines with symmetrical or unsymmetrical diaryliodonium salts.

Copper-assisted preparation of pyridinyl sulfonate esters from hydroxypyridines and sodium sulfinates

An efficient and powerful copper-assisted method for the effective conversion of a broad range of hydroxypyridines and sodium sulfinates into their corresponding pyridinyl tosylates was developed. Key features of this base- and ligand-free protocol include using the cheap and readily available CuBr2 as a medium and the use of sodium sulfinates as formal sulfonylation reagents. A variety of functional pyridinyl tosylates could be formed with good yields, which can easily be converted into C-C and C-N bond-containing compounds.