A new practical method for the synthesis of acetylenes.

✍ Scribed by Jean Boivin; Laurent Elkaim; Paul G. Ferro; Samir Z. Zard

• Publisher: Elsevier Science
• Year: 1991
• Tongue: French
• Weight: 242 KB
• Volume: 32
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)92375-x

✦ Synopsis

The reaction of uoxazol-5-ones derived from J-keto esters and hydroxylamine with soduun nitrite andferrous sulphate in aqueous acenc acid affords the corresponding acetylenes m moderate to good yield

Acetylenes possess an extraordmarily rich and varied chemistry and, over the years, a large number of methods have been developed for introducmg the acetylenic fragmentl. Nevertheless, in view of the central role played by this family of compounds in organic synthesis, new reactions leading to the for-matron of the carbon-carbon triple bond are still needed. In this Letter, we wish to report a new process for converting Rketo esters into acetylenes. Because the former compounds are so readily available, we believe this novel method to be a useful addition to the existmg arsenal of the organic chemist.

Our approach consists m converting first the f3-keto-ester 1 into the correspondmg isoxazol-5one2 2 by reaction wtth hydroxylamine followed by ring cleavage and concomitant acetylene formation through nitrosanon with sodium nitrite and acetic acid as shown in scheme 1.