Conjugated Microporous Polymer as Heterogeneous Ligand for Highly Selective Oxidative Heck Reaction.

A series of pyridine-type ligands containing C≡C bonds were designed and synthesized for selective oxidative Heck reaction. These ligands were utilized as functional units and integrated into the skeleton of conjugated microporous polymers. 6,6'-diiodo-2,2'-bipyridine and 1,3,5-triethynylbenzene were polycondensed via Sonogashira cross-coupling strategy to afford CMP-1 material. The resultant CMP-1 was used as a heterogeneous catalytic ligand for the PdII-catalyzed oxidative Heck reaction with high linear selectivity. The linear selectivity of CMP-1 is about 30 times higher than that of bipyridine-based monomer ligand. This work opens a new front of using CMP as an intriguing platform for developing highly efficient catalysts in controlling the regioselectivity in organic reactions.

Silver(I)-Catalyzed Tandem Sigamatropic Rearrangement/1,3-H Shift/6π Aza-electrocyclization of N-Propargylic Hydrazones: A Mild Synthetic Route to 1,6-Dihydropyridazines.

A highly efficient AgOTf catalyzed [3,3] sigmatropic rearrangement/1,3-H shift/6π aza-electrocyclization cascade reaction of N-propargylic hydrazones has been developed. This method provides a new mild synthetic route to various polysubstituted 1,6-dihydropyridazines including the 3-CF3-substituted ones with high selectivity.

Synthesis of 4-Arylidenepyrazolones by a Gold-Catalyzed Cyclization/Arylidene Group Transfer Cascade of N-Propioloyl Hydrazones.

An efficient gold-catalyzed cyclization/arylidene group transfer cascade reaction of N-propioloyl hydrazones has been developed. This method provides a novel approach for the synthesis of various functionalized 4-arylidenepyrazolones.

Electrochemical synthesis of ß-difluoromethylamide compounds by N-benzenesulfonylacrylamide with difluorine reagents.

A mild and efficient electrochemical method for radical addition, cyclization, and migration reaction was described in this work. A difluoromethyl radical was produced by anodizing CF2HSO2Na. The resulting product was then added to olefin, underwent Smiles cyclization, and migrated to form ß-difluoromethamide compounds after the release of SO2. The process was free from metals and catalysts, gram-grade, and resistant to a variety of electron-rich substrates.

Chemoselective synthesis of substituted pyrazoles through AgOTf-catalyzed cascade propargylic substitution-cyclization-aromatization.

A cascade AgOTf-catalyzed chemoselective approach to 3,5/1,3-disubstitued pyrazoles from propargylic alcohols and para-tolylsulfonohydrazide has been developed. Good chemoselectivity is observed depending on the different substituents in the alkyne moiety of the propargylic alcohols, generating two different kinds of products through different aromatization mechanisms. The pyrazolo[5,1-a]isoquinoline skeleton can also be effectively constructed by this method through a cascade bicyclization process.

Thiophene-Alkyne-Based CMPs as Highly Selective Regulators for Oxidative Heck Reaction.

Thiophenes containing an adjacent C≡C group as ligands for PdII-promoted organic reactions are reported for the first time. These ligands were utilized as catalytic sites and integrated into the skeleton of conjugated microporous polymers. By employing these CMP materials as selective regulators, oxidative Heck reactions between arylboronic esters and electronically unbiased alkenes provide highly selective linear products.

Synthesis of 5,6-Dihydropyrazolo[5,1-a]isoquinolines through Indium(III)-Promoted Halocyclizations of N-Propargylic Sulfonylhydrazones.

A novel method for the preparation of 5,6-dihydropyrazolo[5,1-a]isoquinoline via indium(III)-promoted halocyclizations of N-propargylic sulfonylhydrazones has been developed. The pyrazole and 3,4-dihydroisoquinoline moieties were synchronously formed via a cascade cyclization reaction using easily assembled open-chain compounds. The pyrazole and 3,4-dihydroisoquinoline moieties were formed via a cascade cyclization reaction using easily assembled open-chain compounds.

Synthesis of 5,6-dihydropyrazolo[1,5-c]quinazolines through gold-catalyzed chemoselective bicyclization of N-propargylic sulfonylhydrazones.

An efficient method for the preparation of 5,6-dihydropyrazolo[1,5-c]quinazolines via gold(I)-catalyzed chemoselective bicyclization of N-propargylic sulfonylhydrazones has been developed. This process relies on the chemoselective cyclization of the hydrazone nitrogen instead of the usually favored aniline nitrogen onto the alkyne. The synthetic utility of the current strategy is demonstrated through the synthesis of a potential Eg5/Kinesin spindle protein inhibitor.

Synthesis of polysubstituted pyrazoles by a platinum-catalyzed sigmatropic rearrangement/cyclization cascade.

A highly efficient Pt-catalyzed [3,3] sigmatropic rearrangement/cyclization cascade of N-propargylhydrazones is reported. The process provides expedient access to a variety of highly functionalized pyrazoles. The substrate has good substituted group compatibility, and the bioactive 3-CF3 pyrazoles could be synthesized easily with this method.