Ringtransformationen von Pyrazolinonen �ber Azoolefine - ein neuer Zugang zum 1,2,3-Thiadiazol-System
作者:G. Lutze、Klaus Kirschke、Petra H�bner、Ernst Schmitz、Matthias Ramm、Norbert Krau�
DOI:10.1002/prac.19933350209
日期:——
Elektrophilic attack of thiocyanate/bromine to azoenamine (2 a) yields thiocyanato compound 3 a which cyclizes into 1,2,3-thiadiazolium-salt (5 a) on treatment with perchloric acid. 2-Halo-3-arylazo-propenamides (8) form directly thiadiazolium-salts (11) with KSCN/HOAc. The addition of N- or O-nucleophiles to 11 occurs in the 5-position to form 1,2,3-thiadiazolines (13).