Synthesis of pyrone carbaldehydes, pyrone sulfonium ylides and related epoxides

✍ Scribed by Aziz Shahrisa; Mahnaz Saraei

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2009
• Tongue: English
• Weight: 196 KB
• Volume: 46
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.79

✦ Synopsis

Abstract

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Hexaminium salts of 4‐pyrones 3a, 3b were synthesized by treatment of 2‐(4‐bromomethylphenyl)‐6‐methyl‐4__H__‐pyran‐4‐one 2a and 2‐(4‐bromomethylphenyl)‐6‐phenyl‐4__H__‐pyran‐4‐one 2b with hexamethyl‐enetetramine in chloroform in 71 and 84% yields respectively. Hydrolysis of 3a and 3b in EtOH:H~2~O produced the corresponding aldehydes 4a and 4b in 43 and 58% yields respectively. The reaction of bromopyrones 2b and 2c with dimethylsulfide in MeOH: CH~2~Cl~2~ afforded the corresponding sulfonium salts 5b and 5c in 66 and 65% yields respectively. Treatment of 5b and 5c with arene carbaldehydes such as (Ar = p‐ClC~6~H~4~, o‐ClC~6~H~4~, p‐NO~2~C~6~H~4~, o‐NO~2~C~6~H~4~, p‐FC~6~H~4~, 2‐naphthyl, p‐MeOC~6~H~4~, C~6~H~5~CHCH, p‐MeC~6~H~4~, C~6~H~5~ and 4‐(4‐oxo‐6‐phenyl‐4__H__‐pyran‐2‐yl)‐benzaldehyde 4b) in the presence of sodium hydroxide in CH~3~CN:H~2~O afforded eleven trans‐epoxides in 61–93% yields. J. Heterocyclic Chem., 46, 268 (2009).