The Nature of Tetrazolium Salts and Formazans

✍ Scribed by C. Schiele

• Publisher: John Wiley and Sons
• Year: 1966
• Tongue: English
• Weight: 138 KB
• Volume: 5
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.196606811

✦ Synopsis

ketones. If (If) is heated for 48 h at 130 O C the radioactivity is distributed equally between C-1 and C-5. However, the data collected up to the present suggest that two halogen substituents on C-5 are essential for complete and irreversible pentadiene 1,5-halogen-oxygen exchange: the cis-form of ( l g ) appears merely to enter into an equilibrium with the pyran ( 2 g ) ; the presence of the ketone (3g) in the mixture cannot be ascertained I f complex-forming reagents (FeCI3 or SnC14) are added to ( I ) during the rearrangement, pyrylium salts can be isolated in good yieldr41, a fact that presents strong evidcnce for formation of the pyrans (2) as intermediates.

[Lecture at Saarbriicken (Germany), Jan. 21st, 19661 [VB 988 IE]