Asymmetric Total Synthesis of (+)-21-epi-Eburnamonine Via a Photocatalytic Radical Cascade Reaction

An asymmetric total synthesis of(+)-21-epi-eburnamonine has been achieved.Key features of the synthesis include a visible-light photocatalytic intra-/intramolecular radical cascade reaction to assemble the tetracyclic ABCD ring system,and a highly diastereoselective Johnson-Claisen rearrangement to establish the C20 all-carbon quaternary stereocenter.

Synthesis of arylsulfonyl-substituted indolo[2,1-a]isoquinolin-6(5H)-one derivatives via a TBAI-catalyzed radical cascade cyclization

We have developed a metal-free radical cascade reaction of N-substituted 2-aryl indoles with readily available sulfonyl hydrazides for the rapid construction of arylsulfonyl-substituted indolo[2,1-a]isoquinolin-6(5H)-one derivatives.With the TBAI–TBHP catalytic system,a broad series of structurally diverse indolo[2,1-a]isoquinolin-6(5H)-one derivatives were obtained in moderate to excellent yields.The reaction features mild reaction conditions,operationally easiness,scaled-up feasibility,and high functional-group-tolerance.

Efficient and collective total synthesis of natural products via radical cascade reactions

Subject Code:B02With the support of the National Natural Science Foundation of China,the research team led by Prof.Qin Yong(秦勇)at Sichuan University accomplished a collective synthesis of 33 monoterpenoid indole alkaloids that belong to four families,by developing new photoredox-initiated radical cascade reactions.

Synthesis of highly functional quinazolins via metal-free,visible-light-enabled radical cascade arylation/cyclization of fluorinated imidoyl isothiocyanates

A metal-free,efficient and easy-to-hand protocol for the synthesis of 2-perfluoroalkylquinazolins has been achieved by Eosin B catalyzed radical cascade arylation/cyclization reaction of fluorinated imidoyl isothiocyanates with aryldiazonium Salts.A variety of highly functionalized quinozaline derivatives bearing pharmaceutically important thiol and fluoroalkyl groups were efficiently assembled with broad substrate scope and good functional group tolerance.A series of mechanism experiments indicate that this reaction undergoes a radical cascade arylation/cyclization pathway.

Visible-light-induced radical-cascade alkylation/cyclization of N-methacryloyl-2-phenylbenzimidazole:Access to benzoimidazo[2,1-a]isoquinolin-6(5H)-ones

A metal-free visible-light-induced synthesis of aza-polycyclic aromatic hydrocarbons via cascade alkylation/cyclization of N-methacryloyl-2-phenylbenzimidazole was developed.The reaction was carried out with inactive alkanes and cyclic ethers as alkylation reagents,and phenanthrenequinone(PQ)as a direct hydrogen-atom transfer(HAT)photocatalyst.The desired products were obtained in moderate to good yields at room temperature under air.

Metal-free photo-induced radical C-P and C-S bond formation for the synthesis of 2-phosphoryl benzothiazoles

We reveal here a visible-light promoted phosphorylation of 2-isocyanoaryl thioethers for the first time with concomita nt C(sp3)-S bond cleavage and imidoyl C-S fo rmation.Additionally,this method features the use of 3 mol%organic dye Rose Bengal as the photocatalyst without external transition-metal or peroxide oxidants,and provides a novel and environmentally friendly approach for the preparation of a variety of 2-phosphoryl benzothiazoles in moderate to good yields.

Synthetic studies towards(-)-deserpidine:Total synthesis of the stereoisomer and derivative of (-)-deserpidine

The asymmetric synthesis of 16,17,20-epi-deserpidine and a derivative of(-)-deserpidine has been achieved.Key feature s in the assembly of the pentacyclic framework include a visible-light photocatalytic intra-/inter-/intramolecular radical cascade reaction to construct the tetracyclic ABCD ring system in one-pot and an intramolecularaldol reaction to forge the cyclohexane E ring.