S. Shevelev, I. Dalinger, T. I. Cherkasova
Nov 26, 2001
Citations
0
Influential Citations
18
Citations
Journal
Tetrahedron Letters
Abstract
Abstract The cyclocondensation of 2,4,6-trinitrobenzonitrile with the esters of thioglycolic acid results in the formation of 3-amino-4,6-dinitrobenzo[ b ]thiophene-2-carboxylates 3 . The interaction of 3 with anionic nucleophiles RO − (R=CF 3 CH 2 , CHCCH 2 ), RS − (R=Ph, PhCH 2 , (CH 3 ) 2 CHCH 2 ), N 3 − in NMP or DMF leads to the substitution of only the 4-NO 2 group. The replacement of the electron-donating NH 2 group in 3 with hydrogen unexpectedly and significantly hampers nucleophilic substitution of the nitro group. It is assumed that increased reactivity of the 4-NO 2 in 3 is connected with the twist of this group with respect to the plane of the aromatic ring under the influence of the NH 2 group as indicated by semi-empirical quantum chemical calculations.