Recent Developments in Heck-Type Reaction of Unactivated Alkenes and Alkyl Electrophiles

Cellulose-based fluorescent film probes for the recognition and removal of Hg2+/Hg+ ions

The improved solubility of cellulose, and the enlargement of its application is of importance. Herein, we have synthesized cellulose probes with aggregation-induced emission (AIE) effect, which demonstrates high efficiency and sensitivity in detecting Hg2+ /Hg+ ions. The cellulose underwent esterification with a 11‑carbon chain using pyridine as both catalyst and reaction medium, leading to break off H bonds and a significant decrease in crystallinity. This modification allowed the cellulose to be soluble in dichloromethane (DCM) and toluene. Additionally, long-chain oil-soluble BODIPY fluorescent polymers were synthesized using 2-(dimethylamino) ethyl methacrylate (DMAEMA) as monomer via BODIPY containing RAFT reagent. The oil-soluble BODIPY fluorescent polymers were connected to cellulose through the Heck reaction, leading to the preparation of cellulose fluorescent probes. These probes could be easily dissolved in strong polar organic solvents like N, N-dimethylformamide (DMF) and ethanol, but also in DCM and toluene. They can be made into films and gels. Furthermore, the probe utilizes BODIPY as the fluorophore and CO as the binding recognition site for Hg2+ and Hg+. The detection limits are 50 nM and 60 nM, respectively. The cellulose solubility was improved, and the cellulose based probes could be employed to detect and separate Hg2+ and Hg+.

Recent Advances in Palladium-Catalyzed Asymmetric Heck/Tsuji-Trost Reactions of 1,n-Dienes

Transition-metal catalyzed tandem asymmetric reactions were powerful tools to access various chiral compounds. Many strategies have been developed for the coupling of 1,n-dienes with aryl halides via a tandem Heck/Tsuji-Trost process. However, the control of regio- and stereo-chemistry remains a challenging task. This minireview details the recent advances in the field of asymmetric Heck/Tsuji-Trost reactions catalyzed by palladium complex, which have opened new opportunities and expanded our understanding in this area of research in recent years.

Ligand-free Pd-catalyzed highly selective arylation of activated and unactivated alkenes via oxidative and reductive heck coupling

In this work, an eco-friendly, green, efficient approach for oxidative and reductive Heck-Mizoroki (HM) reactions was developed, which offered acceptable yields from first-pass experiments. Mono-arylation was achieved without the use of ligands, directing groups, or prefunctionalized alkenes. Considering mild reaction conditions, good functional group compatibility, and great regioselectivity, the method can find broad applications in novel medicine and material development and discovery processes.

Divergent and Selective Light Alkene Cross-Coupling

Light olefins are abundantly manufactured in the petroleum industry and thus represent ideal starting materials for modern chemical synthesis. Selective and divergent transformations of feedstock light olefins to value-added chemicals are highly sought-after but remain challenging. Herein we report an exceptionally regioselective carbonickelation of light alkenes followed by in situ trapping with three types of nucleophiles, namely a reductant, base, or Grignard reagent. This protocol enables efficient 1,2-hydrofunctionalization, dicarbofunctionalization, and branched-selective Heck-type cross-coupling of light alkenes with aryl and alkenyl reagents to streamline access to diverse alkyl arenes and complex alkenes. Harnessing bulky N-heterocyclic carbene ligands with acenaphthyl backbones for nickel catalysts is crucial to attain high reactivity and selectivity. This strategy provides a rare, modular, and divergent platform for upgrading feedstock alkenes and is expected to find broad applications in medicinal chemistry and industrial processes.

Dehydrative Allylation of Alkenyl sp2 C-H Bonds

We designed a cooperative catalytic system by combining commercially available Ca(NTf₂)PF₆ and Pd(PPh₃)₄ to address the dehydrative allylation of alkenyl sp² C-H bonds in an environmentally benign manner. A novel C-OH bond cleavage method was found to be crucial for this practical protocol. A variety of alkenes and allylic alcohols equipped with wide-spectrum functional groups can be successfully incorporated into the desired cross-coupling, affording 1,4-dienes with moderate to excellent yields and high stereo- and regioselectivity.

Heck macrocyclization in natural product total synthesis

Covering: 1981-2020 Heck macrocyclization is a logical extension of the award-winning Mizoroki-Heck reaction. Through covalent linking of two otherwise discrete coupling partners, the resultant chimeric substrate is transformed into a large ring with enhanced rigidity and unique functional group disposition. Pioneered in the early 1980s, this methodology has evolved into a competent option for creating diverse macrocycles. Despite its growing influence, hitherto no systematic survey has ever appeared in the literature. The present review delineates the state-of-the-art of Heck macrocyclization in the context of natural product synthesis. Sixteen selected cases, each examined from a different perspective, coalesce into the view that the title reaction is a viable tool for synthesis-enabled macrocycle research.