Synthesis of 5,6-dihydro-2-trifluoromethyl-1,4-dioxin-3-carboxanilides through polymer-bound activated ester: Construction of dihydro-1,4-dioxin

✍ Scribed by Heduck Mah; Kee Hyuk Chang; Kee Dal Nam; Hoh-Gyu Hahn; Su Yeoul Bae

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2000
• Tongue: English
• Weight: 459 KB
• Volume: 37
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570370452

✦ Synopsis

Abstract

A new construction of dihydro‐1,4‐dioxin and a synthesis of 5,6‐dihydro‐2‐trifluoromethyl‐1,4‐dioxin‐3‐carboxanilides 22 through polymer‐bound activated ester are described. An intermediate β‐hydroxy ether 18 was prepared from the substitution reaction of α‐thio‐α‐chloro compound 8 with ethylene glycol followed by treatment with Raney Ni. Replacement of hydroxy by chlorine and then dehydrochlorination afforded trifluoromethyl dihydro‐1,4‐dioxin ester 15. The polymer‐bound trifluoromethyl dihydro‐1,4‐dioxin‐3‐carboxylic acid, 4‐hydroxy‐3‐nitrobenzophenone ester (21) was prepared through the reaction of polystyrene‐bound 4‐hydroxy‐3‐nitrobenzophenone (19) with the trifluoromethyl dihydro‐1,4‐dioxin‐3‐carbonyl chloride (20). Refluxing of 21 with substituted aniline in acetonitrile gave the corresponding carboxanilide 22. The reaction rate depended on the nucleophilicity of nitrogen of the aniline.