Photoinduced Tandem Cyclization of Alkynes with Phenylsulfinic Acids: Access to Sulfone-Substituted Dioxodibenzothiazepines or Dibenzazepines

Abstract

Photoinduced tandem cyclization of alkynes with phenylsulfinic acids has been accomplished, which gives a mild strategy for the preparation of sulfone-substituted seven-membered N-heterocycles. A variety of scaled-up experiments, further trans-formations, and mechanistic studies were also operated in the follow-up work.

Photoinduced Tandem Cyanomethylation/Cyclization of Unsaturated Compounds: Access to Cyanomethylated 7- or 5-Membered N-Heterocycles

“…The detailed protocol for the preparation of the substrates is according to refs − , and in the manuscript, respectively. Meanwhile, the detailed physical data of the starting material 1-s of product 1 were described as follows:…”

“…On the other hand, dibenzazepines and dioxodibenzothiazepines as common 7-membered N -heterocycles have broadly existed in natural products, pharmaceuticals, and biotechnology . A series of above-medium cycles have been efficiently prepared by Li, Xu, Zhong, Wang, and other groups (Scheme a). , Meanwhile, our group also reported some photo- or persulfate-initiated tandem cyclization to access SCN/SCF 3 /ArSO 2 -revised 7-membered heterocycles (Scheme b) . As one of our study issues, we speculated whether cyanomethylated dibenzazepine and dioxodibenzothiazepines could be produced by using bromoacetonitrile as the cyano source.…”

“…According to the above mechanistic studies and literature precedent, ,,− , bromoacetonitrile and unsaturated trifluoroacetamide were performed as model compounds to describe the possible radical process (Scheme ). First, the excited state of the photocatalyst was formed with the help of blue light, which was then oxidized by bromoacetonitrile to access Ir (IV) species and an α-cyano carbon-centered radical.…”

Photochemical difluoromethylation of alkynes: synthesis of CF2H-substituted seven-membered dioxodibenzothiazepines and dibenzazepines

“…18 Furthermore, Xu, Li, and Zhong et al have reported an electrochemical or photocatalytic radical cyclization of alkynes to access diverse functionalized seven-membered dibenzazepines, which are another class of core scaffolds in many biologically active molecules. 19 Despite these achievements, the known methods have some limitations such as the requirement of stoichiometric transition-metal catalysts, expensive photocatalysts or high temperatures. To date, convenient and practical protocols for the synthesis of dioxodibenzothiazepines are still relatively limited.…”