ChemInform Abstract: A New Generation of Alkoxyl Radical Precursors — Preparation and Properties of N-(Alkoxy)-4-arylthiazole-2(3H)-thiones.

✍ Scribed by Jens Hartung; Michaela Schwarz; Ingrid Svoboda; Hartmut Fuess; Maria Teresa Duarte

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 41 KB
• Volume: 30
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199936149

✦ Synopsis

A New Generation of Alkoxyl Radical Precursors -Preparation and Properties of N-(Alkoxy)-4-arylthiazole-2(3H)-thiones.

-Alkylation of the ammonium salts (IV) of N-hydroxythiazolethiones proceeds chemoselectively by O-alkylation to provide the title N-alkoxythiazolethiones (VI) in moderate yields along with the corresponding S-alkyl analogues in less than 5% yields. The N-phenylpentenyloxy derivatives (VIb)-(VIf) are tested for the photo-induced formation of alkoxy radicals. Thus, photolysis of derivatives (VIb)-(VId) in the presence of Bu 3 SnH predominantly affords cis-(phenyl)methyltetrahydrofuran (VIII) by 5-exo-trig cyclization. The cis/trans selectivity as well as the ratio of 5-exo-trig (VIII) to 6-endo-trig (IX) cyclization product is independent on the aryl substituent of compound (VI). As shown for derivative (VIe), it is also independent on the mode of radical generation (photolysis or AIBN induction). Interestingly, for 4-phenylpenten-4-yl derivative (VIf) formation of tetrahydropyran (IX) is preferred.