Fluoroalkyl Radical Mediated Ring Opening Of Methylenecyclopropanes

Due to presence of C=C bond and three-membered ring motifs in the methylenecyclopropanes?MCPs?,and C=C bond was connected to the three-membered ring directly,MCPs are highly strained but still readily accessible molecules.Both C=C bond and the three-membered ring can be reactive sites.Being highly functional compounds with high strain,they have been used as versatile building blocks in synthesis.Due to high strain of MCPs,most reaction conditions of MCPs were mild.In general,fluorinated radical mediated ring-opening of MCPs has received lettle attention.We devolped an efficient synthesis of fluoroalkyl?Rf?substituted homoallylic halides and homoallylic alcohol esters via fluoroalkyl radical mediated ring-opening of MCPs and sequential atom transfer process.The synthesis of MCPs is relatively easy.We used the 1,3-dibromopropane to react with triphenylphosphine to get the Wittig salt compounds.Then the compound reacts with aldehyde or ketone compounds to give MCPs 1 uisng Witting reaction.In the first part,we used reaction of CuI and Rf-I to to generate Rf radical.Then the Rf radical could trigger the radical reaction of MCPs.At last,we can get homoallylic halides in excellent yields.In the second part,we used the RfTMS/CsF/PhI?OCOR?₂ system to react with MCPs which led to homoallylic alcohol esters in moderate to good yields.The atom transfer process is the key step to restart the chain radical process.