A new approach for one-pot,green synthesis of new polycyclic indoles in aqueous solution

Electro-oxidation of phenylamine derivatives（1a and 1b） have been studied in the presence of pyrazolidine-3,5-dione（3） as a nucleophile in phosphate buffer solution mixed with ethanol,using voltammetric and spectroscopic techniques.The obtained results indicated that the oxidized form of phenylamines（2a and 2b） participate in Michael addition type reactions with pyrazolidine-3,5-dione（3） and via ECECCCCC mechanisms convert to the corresponding new polycyclic indoles（12a and 12b）.In the present study,new polycyclic indole derivatives were synthesized with good yields and high purity using a facile,one-pot and environmentally friendly electrochemical method,without any chemical catalysts,toxic solvents and hard conditions.

Electrochemically time-dependent oxidative coupling/couplingcyclization reaction between heterocycles:tunable synthesis of polycyclic indole derivatives with fluorescence properties

A mild and practical protocol for selectively time-dependent dehydrogenative C–C coupling,as well as tandem couplingcyclization reaction between indoles or/and other heteroaromatics via electrochemically oxidative process has been demonstrated.The reaction runs under noble catalyst,external oxidant and inert gas free condition,allowing tunable access to a wide variety of synthetically useful symmetrical or nonsymmetrical heteroarene with aggregation-induced emission(AIE),and polycyclic 3-D indole derivatives with aggregation-caused quenching(ACQ)fluorescence properties.Finally,preliminary mechanistic study indicated that tunable generation of indole cation under various electrolysis potential via regulating Nprotecting group was the key to achieve cross-coupling between indoles and other heteroaromatics.

Catalytic asymmetric dipolar cycloadditions of indolyl delocalized metal-allyl species for the enantioselective synthesis of cyclopenta[b]indoles and pyrrolo[1,2-α]indoles

The development of novel synthons and efficient methods to synthesize chiral polycyclic indoles has been a hot topic in organic synthesis and medicinal chemistry owing to their broad applications in medicines,pesticides,and other functional molecules.Here,we disclosed novel indolyl substituted metal-allyl zwitterionic intermediates through the decarboxylation of conveniently available vinyl indoloxazolidones,which could be regarded as two types of dipolar species through the anionic delocalization.The palladium-π-allyl species tended to serve as an all-carbon 1,3-dipole in the asymmetric[3+2]cycloaddition with electrondeficient alkenes,which furnished polysubstituted cyclopenta[b]indoles with high regio-and stereoselectivities.Meanwhile,the iridium-π-allyl species was recognized as an aza-1,3-dipole in asymmetric[3+2]cycloaddition with in situ generated C1 ammonium enolates,affording pyrrolo[1,2-α]indoles with high diastereo-and enantioselectivities.In addition,the dipolar cycloadditions could be easily scaled-up and several synthetic transformations of the cycloadducts were demonstrated for the rapid synthesis of diverse chiral polycyclic indoles.