Recent advances in cyclization reactions of isatins or thioisatins via C–N or C–S bond cleavage

Abstract

The exploration of new reactivity modes and synthetic methods has always been an attractive goal of organic and medicinal chemistry. As potential raw materials for the efficient construction of nitrogen-...

Sustainable access to benzothiophene derivatives bearing a trifluoromethyl group via a three-component domino reaction in water

“…On the basis of our experimental results and previous literature reports, 14 we proposed a mechanism for this domino reaction (Scheme 5). The reaction could be triggered by the nucleophilic addition of amine to thioisatin to produce intermediate A via a C-S bond cleavage process.…”

Catalytic Heteroannulation for the Synthesis of Quinoline‐4‐Carboxamides Bearing Axial Chirality

“…The classical synthesis of quinoline‐4‐carboxamides relies on amide coupling between quinoline‐4‐carboxylic acids and amines [15] . Recent advances in the isatin‐to‐quinoline strategy have also provided an efficient approach to such valuable 4‐functionalized quinolines [16] . In 2018, a cascade reaction of isatins with 1,1‐enediamines under the catalysis of NH 2 SO 3 H was disclosed by Yan and co‐workers [17] .…”

“…[15] Recent advances in the isatinto-quinoline strategy have also provided an efficient approach to such valuable 4-functionalized quinolines. [16] In 2018, a cascade reaction of isatins with 1,1-enediamines under the catalysis of NH 2 SO 3 H was disclosed by Yan and co-workers. [17] Almost at the same time, the group of Wu and Bathula independently reported the usage of ketoxime acetates to couple with isatins for the introduction of primary amides to the quinoline ring by using different catalytic systems.…”

“…The higher yield (83%) and shorter reaction time were obtained when n-hexane was used (Table 1, entry 15). Finally, the catalyst loading, substrate ratio as well as the effects of temperature and additive on the reaction were explored (Table 1, entries [16][17][18][19][20]. When 20 mol% of Fe(OTf) 3 or 2.0 equiv.…”

Isothiourea-catalysed enantioselective annulation of 2-aminobenzothiophenes with α,β-unsaturated anhydrides

“…As a result, several synthesis methodologies and relative key intermediates have been documented to develop efficient and convenient functionalization of benzothiophene skeletons. 5 However, most asymmetric synthesis strategies for the functionalized benzothiophene moiety are based on electrophilic benzothiophene derivatives such as unsaturated benzothiophenones and azadienes (Scheme 1A). 6…”