A convenient method for synthesis of polyfunctional dihydropyrrole spiro-fused oxindole-2-ones via an organocatalytic tandem Michael/cyclization sequence

A new methodology was developed for the synthesis of spirocyclic oxindoles bearing polyfunctional dihydropyrrole units via an organocatalytic tandem Michael/cyclization sequence. Products bearing adjacent quaternary–tertiary stereocenters were smoothly obtained in high yields (up to 97% yield) with excellent diastereoselectivities up to >20/1.     

Synthesis of 4-aryl-2,3-dihydropyrroles via Rh-catalyzed intramolecular hydroamino-methylation reaction

The rhodium-catalyzed intramolecular hydroaminomethylation reaction, generating 4-aryl-2,3-dihydropyrroles, has been developed. Triphenylphosphine has been proved to be the excellent ligand to prepare the dihydropyrrole derivatives in up to 99% yield. This procedure provides an efficient and simple alternative route to synthesize 4-aryl-2,3-dihydropyrrole derivatives only in one step.     

Synthesis of 7-azabicyclo[2.2.1]heptane-1-carboxylate via silver/ThioClickFerrophos-catalyzed asymmetric 1,3-dipolar cycloaddition of dihydropyrrole ester with N-substituted maleimide

The AgOAc/ThioClickFerrophos-complex catalyzed the 1,3-dipolar cycloaddition of 3,4-dihydropyrrole-2-carboxylates, a precursor of cyclic azomethine ylides, with N-substituted maleimide to give the exo-cycloadducts, that is, 7-azabicyclo[2.2.1]heptane-1-carboxylates, as the major product in moderate yields with a high enantiomeric excess (up to 86% ee) under the optimized conditions. Michael adducts were produced as a minor product.     

A convenient and efficient ring-opening reaction of aziridines with acetylenes and synthesis of dihydropyrroles

In the presence of ^tBuOK, reaction of acetylenes with N-Ts substituted aziridines derived from both cyclic and acyclic alkenes at room temperature gave rise to homopropargylamines in good to high yields and in high regioselectivity. Not only Ph- and Me₃Si-substituted acetylenes but also acetylene itself was suitable reagents. Treatment of ring-opening products with I₂ and AgOAc in the presence of K₂CO₃ provided dihydropyrroles in high yields. One-pot synthesis of dihydropyrroles was also realized by the reaction of aziridines and phenylacetylene in the presence of NaH followed by the treatment with I₂ and AgOAc.     

Palladium‐Catalyzed Enantioselective Narasaka–Heck Reaction/Direct C−H Alkylation of Arenes: Iminoarylation of Alkenes

A palladium‐catalyzed reaction of γ,δ‐unsaturated oxime esters with oxadiazoles afforded dihydropyrroles in good to excellent yields through an intramolecular iminopalladation/intermolecular direct heteroarene C−H alkylation cascade. This unprecedented iminoarylation of alkenes was subsequently realized in an enantioselective manner in the presence of a chiral bidentate phosphine ligand (Synphos).     

Design,synthesis, and insecticidal bioactivities evaluation of pyrrole- and dihydropyrrole-fused neonicotinoid analogs containing chlorothiazole ring

Chlorothiazole ring, as a substituted heterocycle, frequently occurred in structures of various insecticides, and brought positive effect on bioactivity. In purpose to find novel neonicotinoids, a series of pyrrole- and dihydropyrrole-fused neonicotinoid analogs containing chlorothiazole ring were synthesized for the first time. Results of the following biological assays showed that compounds 5a-c achieved good insecticidal activity against Aphis craccivora, and compound 5h exhibited good activity against Nilaparvata lugens.