Tricarbonylmethane acylhydrazones: Reactions under acylating conditions and formation of fused isoxazole derivatives with concomitant NN bond cleavage

✍ Scribed by Somogyi, László ;Sohár, Pál

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 424 KB
• Volume: 1995
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.1995199510268

✦ Synopsis

Abstract

Reactivity of 3‐(1‐acylhydrazonoethyl)‐2__H__‐pyran‐2‐ones 1a–k and 4a–d towards various acetylating agents and nitrous acid, respectively, is studied. Treatment of dehydroacetic acid (DHA) (thio)acylhydrazones 1a, c, f with Ac~2~O/Et~3~N afforded the 3‐(1‐triacetylhydrazinoethenyl) derivative 3a. The analogous coumarin derivative 5 was obtained by treatment of acetylhydrazone 4a with AcCl/PhNMe~2~. With concomitant N–N bond cleavage acylhydrazones 1c–f were converted to the pyrano‐isoxazole 6 by treatment with NaNO~2~/AcOH whereas coumarin derivative 4d was converted to the imine 4e.