Photochemical conversion of 3-azido-2-vinylthiophenes into thienopyrroles and of 2-azidostyrenes into indoles. High migratory aptitude of sulphur substituents

Oxidation of Nonactivated Anilines to Generate N-Aryl Nitrenoids

“…The perfect selectivity of the migration step in both of these oxidative processes spurred us to investigate additional styryl amines that varied the identity of the β-substituent to further probe the selectivity of 3H-indole formation (Scheme 5). 18 While spirocycles 35a and 35b were obtained when the β substituent was changed from a phenyl group to a methyl-or a 2-furyl group, changing R β to an electron-poor sulfone triggered a 1,2-sulfone shift to afford 3H-indole 36c as the only regioisomer. 19,20 Only decomposition products were observed from 34d bearing a 2-pyridyl group as the β substituent.…”

Synthesis of Heterocyclic Compounds Possessing the 4H-Thieno[3,2-b]Pyrrole Moiety

“…The parent heterocycle I was synthesized in 1957 by the reductive cyclization of 3-nitro-2-thienylpyruvic acid, followed by decarboxylation of the product, namely, thieno[3,2- b ]pyrrole-5-carboxylic acid, and also by the reduction of 2 H ,3 H -thieno[3,2- b ]pyrrol-3-one obtained via cyclization of pyrrole-3-thioacetic acid . The general synthetic approach to the substituted alkyl thieno[3,2- b ]pyrrole-5-carboxylates includes transformation of compounds II into numerous derivatives III under treatment of different reagents. − For example, the reported works describe synthesis of alkyl thieno[3,2- b ]pyrrole-5-carboxylates III with the following substituents: 2-formyl, , 2-acetyl, 2-bromo, 2,6-dibromo, 2,3,6-tribromo, 2-nitro, 2,6-dinitro, 3-formyl, 4-benzyl, 4-(2-nitrobenzyl), , 6-dimethylaminomethyl, 6-(1-piperidinylmethyl), 6-cyanomethyl, 6-formyl, , 2-methyl-3-acyl, − 2-methyl-3,6-diacyl, , 2-methyl-4-(2-oxopropyl), and 2-methyl-4-(2-oxo-2-phenylethyl) . Some of the mentioned esters were then hydrolyzed to the corresponding acids, which usually served as convenient starting materials in subsequent tran...…”