A new synthesis, including asymmetric synthesis, of alkylidenecyclopropanes by 1,2-CC insertion of cyclobutylmagnesium carbenoides as the key reaction

✍ Scribed by Nobuhito Nakaya; Shimpei Sugiyama; Tsuyoshi Satoh

• Book ID: 104096535
• Publisher: Elsevier Science
• Year: 2009
• Tongue: French
• Weight: 845 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/j.tetlet.2009.04.038

✦ Synopsis

Treatment of 1-chlorovinyl p-tolyl sulfoxides, derived from ketones and chloromethyl p-tolyl sulfoxide, with lithium enolate of carboxylic acid tert-butyl esters gave adducts in high yields. The adducts were converted to 1-chlorocyclobutyl p-tolyl sulfoxides in four steps in high overall yields. Treatment of the 1-chlorocyclobutyl p-tolyl sulfoxides with cyclopentylmagnesium chloride in THF at À40 °C resulted in the formation of cyclobutylmagnesium carbenoids. The magnesium carbenoid 1,2-CC insertion reaction took place smoothly from the cyclobutylmagnesium carbenoids to afford alkylidenecyclopropanes in good to high yields. An asymmetric synthesis of optically active alkylidenecyclopropane was successfully achieved starting from optically active 1-chlorovinyl p-tolyl sulfoxide.