42327-52-6Relevant articles and documents
Thermally Induced Denitrogenative Annulation for the Synthesis of Dihydroquinolinimines and Chroman-4-imines
Chou, Chih-Hung,Chen, Ying-Yu,Rajagopal, Basker,Tu, Hsiu-Chung,Chen, Kuan-Lin,Wang, Sheng-Fu,Liang, Chien-Fu,Tyan, Yu-Chang,Lin, Po-Chiao
, p. 757 - 765 (2016/03/09)
A rapid growth in synthetic methods for the preparation of diverse organic molecules using N-sulfonyl-1,2,3-triazoles is of great interest in organic synthesis. Transition metals are generally used to activate the α-imino diazo intermediates. Metal-free methods have not been studied in detail, but can be a good complement to transition metal catalysis in the mild reaction conditions. We herein report a novel method for the preparation of 2,3-dihydroquinolin-4-imine and chroman-4-imine analogs from their corresponding N-sulfonyl-1,2,3-triazoles in the absence of metal catalysts. To achieve intramolecular annulation, the introduction of an electron-donating group is required at the meta position of N-sulfonyl-1,2,3-triazole methyl anilines. The inclusion of tailored substituents on the aniline moieties and nitrogen atoms enhances the nucleophilicity of the phenyl π-electrons, thus allowing them to undergo a Friedel-Crafts-type reaction with the highly electrophilic ketenimines. This metal-free method was carefully optimized to generate a variety of dihydroquinolin-4-imines and chroman-4-imines in moderate-to-good yields.
