Methylenecyclopropenes cycloaddition reactions

Pentacylic cage compounds 202 were synthesized through a double cycloaddition reaction to methylenecyclopropene 199, which involves an intermol-ecular 1,3-dipolar cycloaddition of 198 on the endo double bond to give 200 followed by an intramolecular Diels-Alder reaction between a benzylidenecyclo-propane moiety and an ene function (Table 19) [49],... [Pg.40]

Methylenecyclopropenes can function as the 2n addend in Diels-Alder cycloadditions, and it is only the endocyclic double bond that is involved (Section II.G) thus, reaction of 85 with cyclopentadiene affords endo adduct 379 (opposite) exclusively... [Pg.1316]

Benzothiazolium Salts. The benzothiazolium A -phenacylide adds to the endocyclic double bond of methylenecyclopropenes that have no acyl group in the 4-position to give stable [3 + 2] cyclo-adducts (217). This is claimed to be the first example of the formation of stable [3+2] cycloadducts in the reaction of 1,3-dipoles with methylenecyclopropenes. Other cycloadditions of benzothiazolium iV-phenacylide with olefinic dipolarophiles from the same team are also mentioned. Various reactions of other benzothiazolium salts have also been described. " ... [Pg.181]

Big Chemical Encyclopedia