A novel route to cumulenes. The addition of dihalocarbenes to 2,5-dimethyl-2,3,4-hexatriene.

✍ Scribed by Lars Skattebøl

• Publisher: Elsevier Science
• Year: 1965
• Tongue: French
• Weight: 225 KB
• Volume: 6
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)90174-6

✦ Synopsis

Doering and Hoffmann discovered that gem-dihalocycloprqaes can be formed by the addition to olefins of dihalocarbenes, generated frrrm the respective haloform and potassium $-butoxide. An impressive amount of work has since been carried out on this and related reactions.2 Ball and Landor described the addition of dibromocarbene to allenes yielding methylenecyclopropanes, but the formation of diadducts, i.e.spiropentanes, has not been described, nor has successful addition to .s cumulene been reported in the literature. This preliminary communication describes the addition of dichloroand dibromocarbene to 2,k-dimethyl-2,x-pentadiene (I) and 2,5-dimethyl-2,3,4hexatriene (II) to give the corresponding gem-dihalocyclopropane derivatives. -The treatment of the dibromo derivatives with methyllithium afforded cmnulenes, and this sequence of two reactions, starting frOm allenes, consqitutes a novel route to this class of compounds. 5 It appears particularly pro&sing 8s a method for the synthesis of alkyl-substituted cmnulenes.