Synthesis of symmetrical 2,2′,4,4′-tetrasubstituted[4,4′-bioxazole]-5,5′(4H,4′H)-diones and their reactions with some nucleophiles

✍ Scribed by Kenneth K. Andersen; Daniel F. Gloster; Diana D. Bray; Massud Shoja; Anders Kjær

• Book ID: 102892843
• Publisher: Journal of Heterocyclic Chemistry
• Year: 1998
• Tongue: English
• Weight: 703 KB
• Volume: 35
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570350210

✦ Synopsis

Abstract

Several symmetrical 2,2′,4,4′‐tetrasubstituted[4,4′‐bioxazole]‐5,5′(4__H__,4′H)‐diones 1a‐f were obtained by dehydrodimerization of 5(4__H__)‐oxazolones 2a‐f. The configurations of four were established; one by X‐ray crystallography rac‐1c, and three rac‐1a, meso‐1a and rac‐1b by ^1^H nmr spectroscopy of their derivatives. Upon being heated, the bioxazolones isomerized, presumably by breakage of the 4,4′‐carboncarbon bond to form free radicals followed by their recombination. The results of a crossover experiment were consistent with a radical nature for this isomerization reaction. Treatment of three of the bioxazolones rac‐1a, meso‐1a and rac‐1c with methanol and amine nucleophiles led to ester and amide derivatives 7–11 of α,α'‐dehydrodimeric amino acids.