4‐Benzothiatriazine‐1,1(2H)‐dioxides reacted with allenes in the presence of a nickel(0)/(R)‐quinap complex to produce a variety of substituted 3,4‐dihydro‐1,2‐benzothiazine‐1,1(2H)‐dioxides in a regio‐ and enantioselective fashion. An intermediate nickelacycle was generated through denitrogenative activation of the triazo moiety which allowed the intermolecular incorporation of an allene group. quinap=1‐
Redox Cyclization of Amides and Sulfonamides with Nitrous Oxide for Direct Synthesis of Heterocycles
作者:Zhencheng Lai、Chaorong Wang、Jiaming Li、Sunliang Cui
DOI:10.1021/acs.orglett.0c00397
日期:2020.3.6
Herein we report a redox cyclization of amides and sulfonamides with nitrousoxide (N2O) for the direct synthesis of heterocycles. Various amides and sulfonamides could undergo directed ortho metalation (DoM) by treatment with BuLi, and the lithium intermediate could be trapped by N2O gas to achieve redox cyclization. N2O serves as a N-atom donor to mediate the intramolecular coupling of lithium species
1,2,3-Benzotriazin-4(3H)-ones and 1,2,3,4-benzothiatriazine 1,1(2H)-dioxide reacted with isocyanides in the presence of a palladium catalyst to give 3-(imino)isoindolin-1-ones and 3-(imino)thiaisoindoline 1,1-dioxides, respectively, in high yield. An intermediate azapalladacycle was generated through denitrogenation of the triazine moiety, and an isocyanide was incorporated therein.