Palladium-catalyzed intramolecular γ-lactam formation of an aryl halide and an enolate: synthesis of isoindolobenzazepine alkaloids, lennoxamine, 13-deoxychilenine, and chilenine

A facile synthetic path to isoindolobenzazepine alkaloids, lennoxamine, 13-deoxychilenine, and chilenine, was established by employing a palladium-catalyzed intramolecular α-arylation of the ketone, as the key step.     

SYNTHESIS AND PROPERTIES OF NOVEL POLY(IMINO KETONE)S AS HIGH-PERFORMANCE POLYMERS

Di(4-bromophenyl)ketone and various aromatic diamines as the monomers,a series of novel poly(imino ketone)s (PIKs)have been synthesized via palladium-catalyzed aryl amination,which is Hartwig-Buchwald polycondensation reaction.The structures of PIKs are characterized by means of elemental analysis,FT-IR,~1H-NMR and UV-Vis spectroscopy. The results show a good agreement with the proposed structure.The general properties of PIKs are studied by DSC,TG and wide-angle X-ray diffraction,the solubility behavior...     

Palladium-catalyzed synthesis of 1,2,3,4-tetraalkyl-1,4-diarylbutadienes by cross-coupling of zirconacyclopentadienes with aryl iodides

A novelmethod for the synthesis of 1, 2, 3, 4-tetraalkyl-1, 4-diarylbutadienes was developed via palladiumcatalyzed cross-coupling of zirconacyclopentadienes with aryl iodides. Equivalent of CuCl was introduced to promote the reaction. The desired products were obtained in good to excellent yields and several of them were reported for the first time.     

Asymmetric palladium-catalyzed hydroarylation of styrenes and dienes

Alkenes are desirable and highly versatile starting materials for organic transformations, and well-known substrates for palladium catalysis. Typically, these reactions result in the formation of a new alkene product via β-hydride elimination. In contrast to this scenario, our laboratory has been involved in the development of alkene hydro- and difunctionalization reactions, where β-hydride elimination can be controlled. We report herein the development of an asymmetric palladium-catalyzed hydroarylation, which yields diarylmethine products in up to 75% ee. Interestingly, a linear free energy relationship is observed between the steric bulk of the ligand within a certain range and the ee of the reaction.     

Synthesis of benzo-fused five- and six-membered heterocycles by palladium-catalyzed cyclocarbonylation

A novel and simple synthetic methodology, based on palladium-catalyzed cyclocarbonylation reaction, is presented for preparing five- and six-membered benzo-fused heterocycles. A mechanism for the process is also proposed and discussed.     

Palladium-Catalyzed Synthesis of Tetrahydrocarbazoles

The synthesis of tetrahydrocarbazoles from bromoenaminones derived from β-diketones is described. The reaction proceeds by intramolecular cyclization of bromoenaminones involving arylpalladium complexes.     

Synthesis of the CD-ring of the anticancer agent streptonigrin: studies of aryl-aryl coupling methodologies

A series of functionalized 4-bromopyridines, representing the C-ring of the anticancer agent streptonigrin have been prepared and their abilities to undergo Pd-catalyzed cross-coupling with streptonigrin D-ring siloxanes were evaluated. The coupling reaction was generally tolerant to the preparation of hindered CD biaryls; however, the electronic effects of both partners play a pivotal role in the success of the coupling process. Analogs of the CD biaryl were prepared by coupling of aryl siloxane derivatives (D-ring component) with highly functionalized 4-bromopyridines (C-ring); however, the CD biaryl of the natural product could not be prepared in high yield by siloxane coupling due to the facile formation of reduced pyridine under the coupling conditions. Alternatively, the fully functionalized CD biaryl of streptonigrin was prepared using a Suzuki coupling of appropriately functionalized C-ring bromide and D-ring aryl boronic acid. The described approach is highly convergent and readily amenable to the synthesis of analogs.     

Synthesis of trifluoromethylated γ- and β-lactones through the palladium-catalyzed cyclocarbonylation

3-Trifluoromethyl-2(5H)-furanones (γ-lactones) and 3-(2,2,2-trifluoroethylidene)-2-oxetanones (β-lactones) were obtained, respectively through the palladium-catalyzed cyclocarbonylation of (Z)-3-iodo-3-trifluoromethyl allylic alcohols and (Z)-2-iodo-3-trifluoromethyl allyl alcohols.     

Total synthesis of rac-longamide B

rac-Longamide B has been synthesized in six-steps from known starting materials. The synthesis is highlighted by a novel palladium-catalyzed double allylic alkylation of amidopyrroles with 2-butene-1,4-di-tert-butyl dicarbonate.