1-Arylimino-pyrazol-Betaine, Pyrazole und 1,2,4-Triazine aus 3-Arylazo-propens�ure-N-chloroamiden
摘要:
Reaction of 3-arylazo-propenoic acid amides 5 with NaOCl yields N-chloroamides 6 which give under alkaline conditions 1,2,4-triazines 9 and 10 (products of a Hofmann degradation). This reaction competes with an intramolecular electrophilic amination and a 1,2-shift reaction giving I-arylimino-pyrazole betaines 11 and 4-chloroimino-pyrazolones 13. Exchange of the halogen in 11 with nucleophiles leads to further betaines 12. Bis-pyrazole 14 and 1,2,3-triazoles 15 are available from 13b. The X-ray structure analysis of compound 11b is discussed.
Ringtransformationen von Pyrazolinonen �ber Azoolefine - ein neuer Zugang zum 1,2,3-Thiadiazol-System
摘要:
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).