Imidazole-containing diarylether and diarylsulfone inhibitors of farnesyl-protein transferase

Sustainable and practical formation of carbon-carbon and carbon-heteroatom bonds employing organo-alkali metal reagents

Metal-catalysed cross-coupling reactions are amongst the most widely used methods to directly construct new bonds. In this connection, sustainable and practical protocols, especially transition metal-catalysed cross-coupling reactions, have become the focus in many aspects of synthetic chemistry due to their high efficiency and atom economy. This review summarises recent advances from 2012 to 2022 in the formation of carbon-carbon bonds and carbon-heteroatom bonds by employing organo-alkali metal reagents.

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.

Metal-free sulfonylation of arenes with N-fluorobenzenesulfonimide via cleavage of S-N bonds: expeditious synthesis of diarylsulfones

A novel metal-free sulfonylation of arenes with N-fluorobenzenesulfonimide (NFSI) toward the synthesis of diarylsulfones has been developed. The reaction represents a rare example of sulfonylation reaction using NFSI as an efficient sulfonyl donor and the first example of acid-mediated sulfonylation of unactivated arenes with NFSI via selective cleavage of S-N bonds. This protocol provides a concise approach for the construction of pharmaceutically and biologically important diarylsulfones. Applications in the functionalization of natural products (e.g., β-estradiol) and in the synthesis of a key intermediate to an inhibitor of farnesyl-protein transferase, as well as in the gram-scale synthesis of the EPAC2 antagonist, are demonstrated.

Nanosized CdS as a Reusable Photocatalyst: The Study of Different Reaction Pathways between Tertiary Amines and Aryl Sulfonyl Chlorides through Visible-Light-Induced N-Dealkylation and C-H Activation Processes

It has been found that the final products of the reaction of sulfonyl chlorides and tertiary amines in the presence of cadmium sulfide nanoparticles under visible light irradiation are highly dependent on the applied reaction conditions. Interestingly, with the change of a reaction condition, different pathways were conducted (visible-light-induced N-dealkylation or sp³ and sp² C-H activation) that lead to different products such as secondary amines and various sulfonyl compounds. Remarkably, all of these reactions were performed under visible light irradiation and an air atmosphere without any additive or oxidant in benign solvents or under solvent-free conditions. During this study, the CdS nanoparticles as affordable, heterogeneous, and recyclable photocatalysts were designed, successfully synthesized, and fully characterized and applied for these protocols. During these studies, intermediates resulting from the oxidation of tertiary amines are trapped during the photoinduced electron transfer (PET) process. The reaction was carried out efficiently with a variety of substrates to give the corresponding products at relatively short times in good to excellent yields in parallel with the use of the visible light irradiation as a renewable energy source. Most of these processes are novel or are superior in terms of cost-effectiveness, safety, and simplicity to published reports.

Sodium iodide-mediated synthesis of vinyl sulfides and vinyl sulfones with solvent-controlled chemical selectivity

Vinyl sulfides and vinyl sulfones are ubiquitous structures in organic chemistry because of their presence in natural and biologically active compounds and are very frequently encountered structural motifs in organic synthesis. Herein we report an efficient synthesis of vinyl sulfides and vinyl sulfones via transition metal-free sodium iodide-mediated sulfenylation of alcohols and sulfinic acids with solvent-controlled selectivity.

Solvent-controlled selectivity of the elimination/coupling reaction was realized for divergent synthesis of vinyl sulfides and vinyl sulfones. The described protocol is more convenient for the preparation of vinyl sulfide and vinyl sulfone related skeletons.

Regioselective synthesis of arylsulfonyl heterocycles from bromoallyl sulfones via intramolecular Heck coupling reaction

Indoles, benzofurans and benzosultams endowed with arylsulfonyl groups were prepared in two steps from 2-bromoallyl sulfones. ortho-Halosulfonamides and ortho-iodophenol reacted with 2-bromoallyl sulfones in the presence of cesium carbonate to furnish products resulting from a formal vinylic substitution reaction. Palladium-catalyzed intramolecular Heck reaction of these adducts furnished sulfonylated indoles, benzosultams and benzofurans. Isomerization of the double bond participating in the Heck reaction under basic conditions led to the formation of two isomeric products in two cases. Conditions for selectively accessing each of the regioisomeric indoles were developed.

Facile synthesis of biarylmethanes and tetrasubstituted arenes via a base-mediated [3 + 3] benzannulation reaction of Morita–Baylis–Hillman adducts and unsaturated sulfones

A regioselective DBU-mediated [3 + 3] benzannulation reaction of 1,3-bis-sulfonyl propenes and Morita–Baylis–Hillman (MBH) bromides to afford bis-sulfonyl biarylmethanes/arenes is described.

Organic photoredox catalysis enabled cross-coupling of arenediazonium and sulfinate salts: synthesis of (un)symmetrical diaryl/alkyl aryl sulfones

Transition-metal- and oxidant/reductant-free visible-light-mediated synthesis of (un)symmetrical diaryl/alkyl aryl sulfones from aryl diazonium and sulfinate salts employing eosin Y as an organo-photoredox catalyst is reported.

An efficient heterogeneous copper fluorapatite (CuFAP)-catalysed oxidative synthesis of diaryl sulfone under mild ligand- and base-free conditions

We report an efficient method for the synthesis of diaryl sulfones using heterogeneous CuFAP-catalysed coupling of sodium salt of aryl sulfonic acid with phenyl boronic acid.

Synthesis of novel disulfide and sulfone hybrid scaffolds as potent β-glucuronidase inhibitor

Novel series of disulfide and sulfone hybrid analogs (1-20) were synthesized and characterized through EI-MS and (1)H NMR and evaluated for β-glucuronidase inhibitory potential. All synthesized analogs except 13 and 15 showed excellent β-glucuronidase inhibitory potential with IC50 value ranging in between 2.20-88.16μM as compared to standard d-saccharic acid 1,4 lactone (48.4±1.25μM). Analogs 19, 16, 4, 1, 17, 6, 10, 3, 18, 2, 11, 14 and 5 showed many fold potent activity against β-glucuronidase inhibitor. Structure activity relationship showed that substitution of electron withdrawing groups at ortho as well as para position on phenyl ring increase potency. Electron withdrawing groups at meta position on phenyl ring showed slightly low potency as compared to ortho and para position. The binding interactions were confirmed through molecular docking studies.

Three-component oxysulfenylation reaction: two simple and convenient approaches to β-alkoxy sulfides

An unprecedented method for the synthesis of β-alkoxy sulfides via a NaI/HBr-mediated three-component oxysulfenylation reaction of alkenes with arylsulfinic acids and alcohols is reported. Furthermore, I2-promoted oxysulfenylation of alkenes using sodium arylsulfinates instead of arylsulfinic acids to synthesise various β-alkoxy sulfides is also described.

Microwave-assisted regioselective sulfenylation of indoles under solvent- and metal-free conditions

Formation of 3-sulfenylindoles using sulfinic acid as a sulfenylating agent.

Byproduct promoted regioselective sulfenylation of indoles with sulfinic acids

An unprecedented method to synthesise 3-sulfenylindoles is demonstrated via byproduct promoted sulfenylation of indoles with sulfinic acids in the absence of an external catalyst. The reaction selectively afforded structurally diverse indole thioethers in good to excellent yields in 1,2-dichloroethane at 80 °C.

Copper-catalysed Coupling of Aryl Tosylates with Sodium Arylsulfinates

Diaryl sulfones derivatives were easily synthesised from aryl tosylates and sodium arylsulfinates in high yields using [Cu(CH3CN)4]PF6 as catalyst. The transformation is efficient, simple and the starting materials are readily available.

Arylation of lithium sulfinates with diaryliodonium salts: a direct and versatile access to arylsulfones

An efficient, transition-metal-free arylation of lithium sulfinates, which are readily accessible from reactions of organolithium reagents with sulfur dioxide, is described. Based on this method, a practical protocol for the direct transformation of (hetero)arenes and (hetero)aromatic halides into diarylsulfones was developed.

Dapson in heterocyclic chemistry, part V: synthesis, molecular docking and anticancer activity of some novel sulfonylbiscompounds carrying biologically active dihydropyridine, dihydroisoquinoline, 1,3-dithiolan, 1,3-dithian, acrylamide, pyrazole, pyrazolopyrimidine and benzochromenemoieties

N,N'-(4,4'-Sulfonylbis(4,1-phenylene))bis(2-cyanoacetamid) 2 was utilized as a key intermediate for the synthesis of novel dihydropyridines 3, 4, 8, dihydroisoquinolines 5-7, dithiolan 10, dithian 11, acrylamide 12, benzochromenes 17 and 18 and chromenopyridones 19 and 20. Compound 2 was the starting material in the synthesis of the acrylamide derivative 14, the pyrazole derivative 15 and the pyrazolopyrimidine derivative 16. All the synthesized compounds were evaluated for their in vitro anticancer activity against human breast cancer cell line (MCF7). Compound 19 showed the best cytotoxic activity with IC(50) value 19.36 µM. In addition, molecular docking study of the synthesized compounds on the active sites of farnesyltransferase and arginine methyltransferase was performed in order to give a suggestion about the mechanism of action of their cytotoxic activity.

Efficient one-pot synthesis of biologically active polysubstituted aromatic amines

An efficient and modular one-pot synthesis of polysubstituted aromatic amines by a mild reductive amination procedure is described and the biological potential of these nitrogen-centered compounds is demonstrated by growth inhibition of murine connective tissue cells and microscopy-based morphological studies.

Efficient library synthesis of imidazoles using a multicomponent reaction and microwave irradiation

Optimization of Radziszewski's four-component reaction employing a microwave-assisted protocol, led to a small library of 48 imidazoles with a success rate of 65% (conversion > 45%). All three diversity points of the four-component reaction were varied. Aromatic and aliphatic inputs were successfully implemented and mono-, di-, tri- and tetrasubstituted imidazoles with various substitution patterns were synthesized. Furthermore, unsymmetrical diketones could successfully be used which improved the intrinsic diversity of the method significantly. If the unsymmetrical diketone 1,2-phenylpropanedione (R1 and R2) was used two regioisomers were formed. Depending on the type of amine (R4) and aldehyde (R3) applied, regioselectivity was modest to good. Based on these results, a reaction mechanism is proposed.

Structure-based design of imidazole-containing peptidomimetic inhibitors of protein farnesyltransferase

A series of imidazole-containing peptidomimetic PFTase inhibitors and their co-crystal structures bound to PFTase and FPP are reported. The structures reveal that the peptidomimetics adopt a similar conformation to that of the extended CVIM tetrapeptide, with the imidazole group coordinating to the catalytic zinc ion. Both mono- and bis-imidazole-containing derivatives, 13 and 16, showed remarkably high enzyme inhibition activity against PFTase in vitro with IC50 values of 0.86 and 1.7 nM, respectively. The peptidomimetics were also highly selective for PFTase over PGGTase-I both in vitro and in intact cells. In addition, peptidomimetics and were found to suppress tumor growth in nude mouse xenograft models with no gross toxicity at a daily dose of 25 mg kg(-1).

Potent and Selective Farnesyl Transferase Inhibitors

We recently described a novel series of CA(1)A(2)X peptidomimetics as farnesyl transferase inhibitors (FTIs). These compounds possess an N-(4-piperidinyl)benzamide scaffold mimicking A(1)A(2) residue. Extensive exploration of structure--activity relationships revealed that replacement of cysteine by substituted benzylimidazoles provided nanomolar FTIs with in vitro activities (18e, IC(50) = 4.60 nM on isolated enzyme, EC(50) = 20.0 nM for growth inhibition on a tumor cell line). The molecular docking of 18e and 19e in the active site of the enzyme provided details of key interactions with the protein and showed that the methionine or phenylalanine residue fits into the aryl binding site.

Synthesis and activity of 1-aryl-1′-imidazolyl methyl ethers as non-thiol farnesyltransferase inhibitors

A series of imidazole-containing methyl ethers (4-5) have been designed and synthesized as potent and selective farnesyltransferase inhibitors (FTIs) by transposition of the D-ring to the methyl group on the imidazole of the previously reported FTIs 3. Several compounds such as 4h and 5b demonstrate superior enzymatic activity to the current benchmark compound tipifarnib (1) with IC(50) values in the lower subnanomolar range, while maintaining excellent cellular activity comparable to tipifarnib. The compounds are characterized as being simple, easier to make, and possess no chiral center involved.

Unsymmetrical Diaryl Sulfones and Aryl Vinyl Sulfones through Palladium-Catalyzed Coupling of Aryl and Vinyl Halides or Triflates with Sulfinic Acid Salts

The palladium-catalyzed reaction of sulfinic acid salts with a wide variety of aryl and vinyl halides or triflates provides unsymmetrical diaryl sulfones and aryl vinyl sulfones in good to excellent yields. The reaction is strongly influenced by the presence of nBu4NCl, and the use of Xantphos, a rigid bidentate ligand with a wide natural bite angle, was found to be crucial for the success of the reaction. With neutral, electron-rich, and electron-poor aryl iodides best results were obtained by using Pd2(dba)3, Xantphos, Cs2CO3, and nBu4NCl, in toluene at 80 degrees C. Two general procedures were employed with aryl bromides and triflates: sodium p-toluenesulfinate, Pd2(dba)3, Xantphos, Cs2CO3, 120 degrees C, in toluene with nBu4NCl (procedure A: neutral, electron-rich, and slightly electron-poor aryl bromides or triflates) and without nBu4NCl (procedure B: electron-poor aryl bromides or triflates). With vinyl triflates best results were obtained at 60 degrees C omitting nBu4NCl.