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Organic Synthesis with N‐Heterocyclic Carbenes of Indazole: Synthesis of Benzo(thio)imidates, Benzo[ d ][1,3]thiazines and Quinazoline‐4‐thiones
Author(s) -
Guan Zong,
Nieger Martin,
Schmidt Andreas
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201500331
Subject(s) - chemistry , indazole , deprotonation , ring (chemistry) , thio , reagent , combinatorial chemistry , medicinal chemistry , organic synthesis , organic chemistry , stereochemistry , catalysis , ion
The N‐heterocyclic carbenes of indazole, generated by deprotonation of indazolium salts, proved to be versatile starting materials for organic synthesis. They undergo ring‐opening reactions to generate ketenimines which readily add thiols thus affording what are, to the best of our knowledge, the first examples of 2‐anilinobenzothioimidates. Water converts the ring‐opened intermediates into functionalized 2‐anilinobenzamides which can be thionated with Lawesson's reagent and subsequently cyclized with formaldehyde and propionaldehyde, respectively, to give benzo[ d ][1,3]thiazines and quinazoline‐4‐thiones. The outcome of the cyclization depends upon the thiobenzamide substitution pattern.