Pd-Catalyzed Aerobic Synthesis of Allylic Sulfones from Allylic Alcohols and Sulfonyl Hydrazines in Water

A mild and green synthesis of allylic sulfones from allylic alcohols and sulfonyl hydrazines was developed in water media. The simple and commercially available Pd(PPh3)4 is used as the best catalyst, and the reaction can proceed smoothly at 40 °C under air. This new method does not require the common nitrogen protection and organic media, and can be readily scaled up in gram scale, showing the good practicality value.

Expedient Synthesis of Alkyl and Aryl Thioethers Using Xanthates as Thiol-Free Reagents

Thioethers are critical in the fields of pharmaceuticals and organic synthesis, but most of the methods for synthesis alkyl thioethers employ foul-smelling thiols as starting materials or generate them as by-products. Additionally, most thiols are air-sensitive and are easily oxidized to produce disulfides under atmospheric conditions; thus, a novel method for synthesizing thioethers is necessary. This paper reports a simple, effective, green method for synthesizing dialkyl or alkyl aryl thioether derivatives using odorless, stable, low-cost ROCS2K as a thiol surrogate. This transformation offers a broad substrate scope and good functional group tolerance with excellent selectivity. The reaction likely proceeds via xanthate intermediates, which can be readily generated via the nucleophilic substitution of alkyl halides or aryl halides with ROCS2K under transition-metal-free and base-free conditions.

One-pot synthesis of 11-sulfenyl dibenzodiazepines via tandem sulfenylation/cyclization of o-isocyanodiaryl amines and diaryl disulfides

A one-pot sulfenylation/cyclization of o-isocyanodiaryl amines has been described for the preparation of 11-sulfenyl dibenzodiazepines. This AgI-catalyzed reaction covers an unexplored tandem process to give seven-membered N-heterocycles. This transformation shows a broad range of substrate scope, simple operation, and moderate to good yields under aerobic conditions. Diphenyl diselenide can also be produced in an acceptable yield.

Unconventional approaches for the introduction of sulfur-based functional groups

Organosulfur compounds have a pivotal role in the functionalities of many natural products, pharmaceuticals and organic materials. For these reasons, the search for new methodologies for the formation of carbon-sulfur bonds has been the object of intensive work for organic chemists. However, the proposed strategies suffer from various drawbacks, such as volatility, toxicity, and instability of the sulfur sources or the use of VOC solvents. In this review, we summarise the recent protocols which have the goal of obtaining sulfones, thioethers, thiazines, thiazepines and sulfonamides in an unconventional and/or sustainable way. The use of starting materials less invasive and toxic with respect to the traditional reagents, alternative solvents such as water, ionic liquids or deep eutectic solvents, the exploitation of ultrasound and electrochemistry, increasing the efficiency of the process, are reported. Moreover, representative reaction mechanisms are also discussed.

Highly selective C3-H iodination of pyrrolo[1,2-a]quinoxalines

We report a C3-H direct iodination of pyrrolo[1,2-a]quinoxalines with TBAI or I2; a series of novel 3-iodopyrrolo[1,2-a]quinoxaline derivatives were obtained with excellent regioselectivity and broad substrate scope. Mechanism studies show that a catalytic amount of p-toluenesulfonic acid significantly promotes the selectivity and conversion of the reaction. Notably, the reaction can be performed on a gram scale, and the iodinated products can be further transformed into potentially biologically active pyrrolo[1,2-a]quinoxaline derivatives by palladium-catalyzed coupling reactions.

Exploration of fluorescence behavior of an imidazolium-based chemosensor in solution and in the solid state and its turn-on response to Al3+ in pure aqueous medium

An imidazolium-based quinoline framework is constructed, and its fluorescence behaviour studies with fluorescence turn-on chemosensory response to the selective detection of Al³⁺ in aqueous medium are discussed in detail.

Preventing Pd–NHC bond cleavage and switching from nano-scale to molecular catalytic systems: amines and temperature as catalyst activators

Heating Pd/NHC complexes with aliphatic amines induces Pd–NHC bond cleavage, while treating the complexes with primary or secondary aliphatic amines in the presence of strong bases promotes the activation of molecular Pd/NHC catalysis.

Aryldithiocarbamates as thiol alternatives in Cu-catalyzed C(aryl)-S coupling reactions using aryldiazonium tetrafluoroborate salts

An efficient method for the synthesis of unsymmetrical diaryl sulfides has been developed by the C-S cross coupling of aryldithiocarbamates and aryldiazonium salts in the presence of CuI-2,2'-bipyridine and Zn. Aryldithiocarbamate compounds have been used here as thiol substitutes. The protocol shows wide substrate scope and good yields of the products.

Iodine-mediated sulfenylation of 4-hydroxycoumarins with sulfonyl hydrazides under aqueous conditions

An efficient, metal-free approach to the synthesis of sulfenylated coumarins based on the iodine catalyzed regioselective sulfenylation of 4-hydroxycoumarins with arylsulfonyl hydrazides was developed under mild conditions in water.