Temporary Molybdenum η6-Coordination Enables Selective and General Dearomative 1,2-Hydrofunctionalization of Benzenes.

A novel photocatalyzed trifluoromethylthio-trifluoromethylation of alkenes has been developed, using CF3SO2Na as both CF3 and SCF3 source. This photocatalyzed dual-oxidative strategy, which combine...

Chiral sulfones are important structural motifs in organic synthesis because of their widespread use in pharmaceutical chemistry. In particular, chiral allylic sulfones have drawn particular interest because of their synthetic utility. However, enantioselective synthesis of 1,3-disubstituted unsymmetrical chiral allylic sulfones remains a challenge. In this article, we report a protocol for (R)-DTBM-Segphos/Pd-catalyzed regio- and enantioselective hydrosulfonylation of 1,3-dienes with sulfinic acids, which provides atom- and step-economical access to 1,3-disubstituted chiral allylic sulfones. The reaction occurs under mild conditions and has a broad substrate scope. Combined experimental and computational studies suggest that the reaction is initiated by a ligand-to-ligand hydrogen transfer followed by a C-S bond reductive elimination via a six-membered transition state. Steric repulsion between the olefinic C-H of the substrate and the tert-butyl group of (R)-DTBM-Segphos was found to be a key factor in the enantiocontrol.

Hydrochlorination of unsaturated hydrocarbons is a fundamental reaction scheme in organic synthesis, with the traditional acid-mediated approaches proceeding in Markovnikov selectivity and direct access to anti-Markovnikov hydrochlorination products being a longstanding pursuit. Previous efforts were restricted to multistep syntheses, stoichiometric chlorine and hydride sources, and/or highly oxidative photocatalysis, resulting in limited scope, and low regioselectivity in some cases. Thus, the development of redox-neutral hydrochlorination with high anti-Markovnikov regioselectivity compatible with both alkenes and alkynes remains important. Here we report a photocatalytic anti-Markovnikov hydro- and deuterochlorination of unsaturated hydrocarbons enabling access to diverse alkyl and alkenyl chlorides regio- and stereo-selectively. Broad scope (125 examples), mild conditions and regio- and isotopo-divergent syntheses are demonstrated. Critical to success is leveraging ligand-to-metal charge transfer (LMCT) photoreactivity of earth-abundant iron and hydrogen atom transfer (HAT) reactivity of redox-active thiol. This cooperative system offers a powerful strategy for anti-Markovnikov hydrofunctionalization of unsaturated hydrocarbons.

Design, Synthesis, and Applications of <i>ortho</i> -Sulfur Substituted Arylphosphanes

Palladium catalysis plays a pivotal role in organic synthesis, encompassing applications in cross-couplings and hydrogenations, among other transformations. Recent progress in palladium chemistry has helped enable catalytic dearomative functionalizations. In particular, catalysis involving benzyl–palladium species has been applied to achieve dearomative functionalization of a wide range of aromatic systems, including challenging substrates such as electronically unbiased benzenes, without the need to use an excess amount of the arene starting materials. This review primarily focuses on dearomative functionalization via benzyl–palladium species, incorporating applications of these methodologies in the synthesis of natural products.

gem-Difluoropropargyl bromides are versatile intermediates in organic synthesis, but have rarely been employed in transition-metal-catalyzed cross-coupling reactions. The first palladium-catalyzed gem-difluoropropargylation of organoboron reagents with gem-difluoropropargyl bromides is now reported. The reaction proceeds under mild reaction conditions with high regioselectivity; it features a broad substrate scope and excellent functional-group compatibility and thus provides an attractive approach for the synthesis of complex fluorinated molecules, in particular for drug discovery and development.

Abstractgem‐Difluoropropargyl bromides are versatile intermediates in organic synthesis, but have rarely been employed in transition‐metal‐catalyzed cross‐coupling reactions. The first palladium‐catalyzed gem‐difluoropropargylation of organoboron reagents with gem‐difluoropropargyl bromides is now reported. The reaction proceeds under mild reaction conditions with high regioselectivity; it features a broad substrate scope and excellent functional‐group compatibility and thus provides an attractive approach for the synthesis of complex fluorinated molecules, in particular for drug discovery and development.

Copper-Catalyzed Ring-Opening/Borylation of Cyclopropenes

The development of mild and practical strategies to produce value-added fine chemicals directly from inexpensive and readily available commodity chemicals is actively pursued by chemists. However, the application of feedstock chemical dichloromethane (DCM) as the C1 source in organic synthesis is still in its infancy. Herein, we describe a multicomponent strategy for the chemoselective synthesis of valuable 1,4,2-dioxazoles by using DCM as a C1 source. Critical to the success of this process is tuning of the type of nucleophiles to inhibit the easily-occurring side reactions. This approach features mild and simple conditions, excellent chemoselectivity, metal free, and broad substrate scope covering different types of nucleophiles. Furthermore, its synthetic utility is further demonstrated by the preparation of deuterated 1,4,2-dioxazoles, the late-stage functionalization of complex molecules and large-scale synthesis. Preliminary mechanistic studies indicate the dual roles of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as both a proton scavenger and a nucleophilic catalyst. This work provides not only a platform for DCM application, but also an excellent complementary strategy to the established 1,4,2-dioxazoles synthesis.

Pyrimidines, fundamental constituents of nucleic acids, pharmaceuticals, and agrochemicals, represent crucial scaffolds in organic synthesis owing to their electron-deficient aromatic character and multifaceted reactivity. This review meticulously assesses three distinct methodologies for the direct activation of C–H bonds in pyrimidines and associated heteroarenes bearing a pyrimidine moiety: transition-metal-catalyzed processes, metal-free techniques, and photochemical approaches. Metal-catalyzed strategies, utilizing catalysts such as palladium, nickel, or copper, facilitate the formation of C–C and C–N bonds with high regioselectivity, exemplified by the C(5)-arylation of 2-amino pyrimidines and the C(7)–H activation in pyrazolo[1,5-a]pyrimidines. Metal-free methodologies, which exploit Minisci-type radical reactions involving persulfates or phosphonium intermediates, provide sustainable functionalization pathways under mild reaction conditions. Photochemical methodologies, incorporating visible-light-driven photocatalysts such as eosin-Y or iridium complexes, facilitate radical-mediated arylations while offering environmental advantages. Through a comprehensive analysis of efficiency, regioselectivity, and scalability, this review also highlights significant progress in the synthesis of bioactive heterocycles, addresses pertinent challenges in green chemistry, and delineates avenues for future advancements in pyrimidine-centric therapeutics and innovative materials.

A palladium and iodine-cocatalyzed 5-exo-dig aza-thiocyclization of 8-alkynylnaphthalen-1-amines for the synthesis of (E)-2-alkylene-1,2-dihydrobenzo[cd]indole thioethers is reported. As a result of broad reaction scope, simple operation, mild conditions, and high stereoselectivity and regioselectivity, this reaction should have potential utility in organic synthesis.

Visible-light photoredox-catalyzed selective carboxylation of C(sp3)−F bonds with CO2

Fully substituted heterofunctionalized triazoles can be prepared by indirect and direct approaches. The indirect strategies are well‐established but have limitations. Herein, we developed a direct methodology to access fully substituted 5‐thiocyanato‐1,2,3‐triazoles with high regioselectivity from the azide‐internal thiocyanatoalkyne cycloaddition reaction under mild conditions. This is the first time that fully substituted 5‐thiocyanato‐1,2,3‐triazoles have been prepared and the first time an AAC/nucleophilic substitution cascade reaction have been used to generate various fully substituted triazolyl−organosulfurs, such as 5‐sulfur‐triazoles and 5‐sulfinylcyanato‐triazoles from common internal thiocyanatoalkyne precursors. This approach features a broad substrate scope (34 examples), good compatibility with water and air, high yields (up to 85%) and excellent regioselectivity (more than 20:1).magnified image

Ni-catalyzed enantioselective [2 + 2 + 2] cycloaddition of malononitriles with alkynes

The implementation of green chemistry (GC) in various aspects of chemistry to overcome the problems of health, safety for workers, in addition to the environmental problems is associated with compounds from their manufacturing, use and disposition as waste. GC is a rapid promising branch of chemistry. GC is a manner that maximizes its benefits while removed its adverse impacts by the application of principles. The principles of GC focused on methods that deals with avoidance of waste, maximize atom economy, less harmful chemical formed, metathesis, synthesized safer chemicals, using safer solvents, auxiliaries, renewable Feedstocks, softer catalysts other than heavy metals, biocatalysts, avoid the formation of chemical derivatives, develop energy efficient synthesis, progress of safer chemistry methods for accident avoidance. GC is interested for research and alternative improvement on many practical phases of organic compounds synthesis. GC intended for less toxic solvents but in recent years new methods have been developed where organic synthesis can be performed without solvents, mild conditions and low energy consumption. New approaches have promoted the use of alternative methods or “green” solvents. The new field of “green” solvents in organic compounds synthesis has been extended and gives some idea about green solvent, green catalyst, and green techniques for green synthesis.