Generation and Diels-Alder Trapping of 4,5-Bis(bromomethylene)-4,5-dihydrothiazole

✍ Scribed by Karine Jouve; Félix Pautet; Monique Domard; Houda Fillion

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 273 KB
• Volume: 1998
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(199809)1998:9<2047::aid-ejoc2047>3.0.co;2-z

✦ Synopsis

Treatment of 4,5-bis(dibromomethyl)thiazole (1a) with of the cycloadditions between 2a and naphthoquinones 6 agrees with the predictions of the frontier molecular orbital sodium iodide in DMF led to 4,5-bis(bromomethylene)-4,5dihydrothiazole (2a). Trapping the latter in situ with theory. In contrast, the regioselectivity observed from 2a and acrylate dienophiles 12, similar to that previously obtained dienophiles afforded directly the aromatized cycloadducts. Starting with 5-hydroxynaphthoquinone or its 2-and 3-with 5-bromomethylene-4-methylene-4,5-dihydrothiazole (2b), is opposite to that predicted and could be better bromo derivatives 6 gave a mixture of the tetracyclic quinones 10 + 11 from which the 1,6-regioisomer 10 accomodated by a competitive Michael addition followed by a cyclization-elimination step. predominates. Using acrylate dienophiles gave 6-substituted benzothiazoles 13 as the major products. The regiochemistry