Free Radical Reaction between 1,6-Dienes and P-Toluenesulfonyl Cyanlde

A sulfonyl-radical-induced addition-cyclization reaction of 1,6-dienes with p-toluenesulfonyl cyanide giving functionalized cyclopentane systems is described.     

One-pot synthesis of 1-aryl-3-methyl-1,3-dienes using methallyl(trimethyl)silane and aldehydes and their low temperature (Z)→(E) isomerization induced by sulfur dioxide

2-Methylprop-2-ene-1-sulfonyl fluorides can be easily prepared via the ene reaction of methallylsilanes and SO₂. In the presence of a base, aldehydes and 2-methylprop-2-ene-1-sulfonyl fluorides give 1,3-(E) and (Z)-dienes. Their (Z)→(E) isomerization by classical means fails or leads to their polymerization. It is shown that SO₂ can isomerize 1-aryl-3-methyl-1,3-dienes at low temperature, without formation of sulfolenes (cheletropic addition/elimination). Preliminary mechanistic studies suggest that SO₂ adds to 1,3-dienes forming 1,4-diradical intermediates that are responsible for the (Z)→(E) isomerizations.     

Silver(I)-mediated reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides:Unexpected formation of vinvl sulfones

A novel reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides was performed in the presence of silver nitrate or triflate.Conjugated vinyl sulfones as dramatic products were obtained in moderate yields and with Z-selectivity.A free radical mechanism has been proposed to account for the formation of the products.     

Synthesis,characterization and biological evaluation of some novel sulfonylthiosemicarbazides

Abstract

A series of thiosemicarbazides were synthesized and structurally characterized by spectroscopic techniques (NMR, FT-IR) besides elemental analysis. These compounds were evaluated for their cytotoxicity against human breast cancer cell line MCF7 and prostate cancer cell line PC3 and nonmalignant fibroblast L929 cell line by MTT assay. Among the compounds, N-[2-(4-chlorophenyl)ethyl]-2-[(4-methylphenyl)sulfonyl]hydrazinecarbothioamide (3d) and 2-[(4-methylphenyl)sulfonyl]-N-[4-(trifluoromethoxy)phenyl]hydrazinecarbothioamide (3f) were found to display significant cytotoxicity with IC₅₀ of 13.87?μM (against PC3 cell line) and 1.47?μM (against MCF7 cell line), respectively. These compounds were non-cytotoxic to normal cell line with IC₅₀>100?μM. Western blotting studies demonstrated that compound 3f induced apoptosis and caused cell death in the MCF7 and PC3 cell lines via an increase in Bax protein expression and a slight decrease in Bcl-2 protein expression. The gene expression ratio Bax/Bcl-2 showed the induction of mitochondrial apoptosis in cancer cell lines. All of synthesized compounds have also been tested for antioxidant activity and all compounds achieved strong inhibition of the DPPH radical. These findings showed that compound 3f, displays potential to be further explored in the development of new anticancer agents.     

Regioselective Synthesis of Polyheterocycles From 4-Cyclohex-2-ENYL-3-Hydroxy-1-Methylquinolin-2(1H)-One

4-Cyclohex-2-enyl-3-hydroxy-1-methylquinolin-2(1H)-one (4) was prepared in 90% yield by the thermal [3,3]sigmatropic rearrangement of 3-cyclohex-2-enyloxy-1-methylquinolin-2(1H)-one (3) in refluxing chloroben-zene for 10 h. Compound (4) was cyclised through a sequence of reactions viz. i) acetylation ii) addition of bromine and iii) treatment of the acetyl dibromo compound (6) with base to give a bicyclic product (7) in 90% yield. Treatment of compound 4 with pyridine hydro-bromide perbromide in dichloromethane at 0–5° C afforded a cyclic product 8 in excellent yield. Compound 4 when treated with cold conc. sulphuric acid at 0–5° C furnished the bicyclic product 12 in 89% yield.     

Conformational change in a urea catalyst induced by sodium cation and its effect on enantioselectivity of a Friedel-Crafts reaction

While developing bis-camphorsulfonyl urea as a hydrogen-bonding catalysts, we discovered that the native conformation of the catalyst is unsuitable for inducing enantioselectivity. By complexing the catalyst with weakly Lewis acidic sodium cations, we were able to change the conformation of the catalyst and attain a significant improvement in the selectivity. We provide structural information from X-ray crystallography to show that the uncomplexed catalyst is indeed in an unfavorable conformation. Infrared and Raman spectroscopic studies show that sodium binds the catalyst through the carbonyl and sulfonyl groups. Simulated IR and Raman spectra match well with the experimentally recorded spectra, thereby corroborating the proposed conformational change. This result shows that weak Lewis acids can be used to tune the conformation of hydrogen-bonding catalysts and enhance the selectivity of reaction catalyzed by these systems.     

Recent progress in the synthesis of sulfonyl fluorides for SuFEx click chemistry

Since the sulfur(VI) fluoride exchange reaction (SuFEx) was introduced by Sharpless and co-workers in 2014, this new-generation click chemistry has emerged as an efficient and reliable tool for creating modular intermolecular connections. Sulfonyl fluorides, one of the most important sulfur(VI) fluoride species, have attracted enormous attention in diverse fields, ranging from organic synthesis and material science, to chemical biology and drug discovery. This review aims to introduce seminal and recent progresses on the synthetic methods of sulfonyl fluorides, which include aromatic, aliphatic, alkenyl, and alkynyl sulfonyl fluorides. While not meant to be exhaustive, the purpose is to give a timely overview and insight in this field, and stimulate the development of more efficient synthetic methods of sulfonyl fluorides.     

Synthesis of novel iodo derived bicalutamide analogs

A series of optically active nonsteroidal selective androgen receptor modulators with structures analogous to bicalutamide was prepared by replacing the trifluoromethyl group with iodine and the sulfonyl linker by oxygen.     

Sulfonyl hydrazides as sulfonyl sources in organic synthesis

While sulfonyl hydrazides are widely utilized in organic synthesis, it is only in recent years that they have emerged as powerful sulfonyl sources. The hydrazinyl group can be readily removed from sulfonyl hydrazides under thermal, basic, oxidative, radical, and/or transition metal-catalyzed conditions, and subsequently, the remaining sulfonyl groups are able to form carbon-sulfur, sulfur-nitrogen, sulfur-halogen, sulfur-sulfur, and sulfur-selenium bonds with a wide variety of organic compounds, providing alternative approaches to the preparation of sulfones, sulfonamides, sulfonyl halides, thiosulfonates, and selenosulfonates. Moreover, some of the carbon-sulfur bond-forming reactions have been successfully applied to the construction of carbocycles, heterocycles, and stereogenic centers.     

Green and mild laccase-catalyzed aerobic oxidative coupling of benzenediol derivatives with various sodium benzenesulfinates

The oxidative coupling reaction between hydroquinone or catechols and various sodium benzenesulfinates was investigated using the laccase from Trametes versicolor, in the presence of O₂ in a phosphate buffer solution at room temperature to afford sulfonyl benzenediols in 75–95% yield.