Visible Light‐Mediated Construction of Sulfonated Dibenzazepines

Abstract

Photocatalysis| Sulfonated dibenzazepines | Radical reactions | Ugi reaction | AnnulationA new method to access sulfonated dibenz[b,e]azepines via visible-light photoredox catalysis is described. Employing inexpensive and commercially available sulfonyl chlorides to form the sulfonyl radicals enables the alkyne addition reaction followed by a 7-membered radical cyclization step to furnish sulfonated dibenzazepines. In addition, an Ugi-type multicomponent reaction (MCR) for the synthesis of o-aminophenylacetylene derivatives can also be used as a rapid substrate synthesis method for the cascade radical cyclization protocol to obtain a series of highly functionalized sulfonylated dibenzazepines, which undoubtedly greatly simplifies the synthetic steps of the dibenzazepine compounds that are important core structures in pharmaceuticals.

The synthesis of seven- and eight-membered rings by radical strategies

“…These compounds could be afforded by combining commercially available sulfonyl chloride and readily available N -benzyl- N -(2-ethylpropyl)amides, using fac -Ir(ppy) 3 as a photocatalyst, Cs 2 CO 3 as a base, and irradiation with blue light under DCE (Scheme 28). 55 Specifically, highly-functionalized seven-membered nitrogen heterocycles were rapidly assembled in a single step by the combination of Ugi and radical tandem cyclization strategies. The only demerit is that they failed to afford the desired product when N -Ts-protected substrate was used.…”

Free Radical Promoted Trifluoromethylthiolation of Alkynes to Access SCF3-Containing Dibenzazepines or Dioxodibenzothiazepines

“…The detailed protocol for preparation of AgSCF 3 and aryl acetylenes was according to refs , , , and − , respectively.…”

“…Because of its valuable biological and chemical activities, many strategies for the syntheses of dibenzazepines (or their derivatives) have been reported by many groups . Very recently, radical cyclization of N -benzyl- N -(2-ethynylaryl)­amides to access various dibenzazepines became a kind of research hot spot. − Despite these achievements, to the best of our knowledge, the radical-induced synthesis of SCF 3 - substituted dibenzazepines via a cascade cyclization pathway is rarely reported now. On the basis of our previous studies, we finally achieved a simple access to SCF 3 -containing dibenzazepines by the free radical cascade reaction of N -benzyl- N -(2-ethynylaryl)­amides with AgSCF 3 .…”

Photocatalyst-, metal- and additive-free regioselective radical cascade sulfonylation/cyclization of benzimidazole derivatives with sulfonyl chlorides induced by visible light

“…11 Despite the significance of these developments, the successful application of the above-mentioned protocols often requires external photocatalysts, transition metals, or additives to facilitate the single electron transfer (SET) process. 12 Therefore, it is greatly appealing to develop more environmentally benign synthetic methods to access sulfonyl radicals under photocatalyst- and additive-free conditions.…”