Kinetics of Strain-Activated Intramolecular Diels-Alder Reactions Between Furan and Bicyclopropylidene as well as Methylenecyclopropane Moieties

Highly Selective Gold-Catalyzed Arene Synthesis

“…This would be quite similar to the activiation of C−C multiple bonds for nucleophilic addition mentioned above. , Now an intramolecular Diels−Alder reaction could provide 10 . Usually furans are notorious unreactive diene partners in Diels−Alder reactions that even in intramolecular cases 17 react only if the dienophile is activated by at least one electron withdrawing group or high pressure is applied for strain-activated olefins …”

“…Usually furans are notorious unreactive diene partners in Diels-Alder reactions that even in intramolecular cases 17 react only if the dienophile is activated by at least one electron withdrawing group or high pressure is applied for strain-activated olefins. 18 In the next step the oxygen bridge must be broken, and this could either be induced by gold(III) acting as a Lewis acid (forming 12) or by Au(I) which forms a Au(III)-stabilized pentadienyl cation 11. Then either the nucleophilic oxygen atom or external water may serve as nucleophiles, and possible intermediates are 13 and 14.…”

Correlation between pressure and steric interactions in organic reactions

“…They involved furans tethered by bicyclopropylidene and methylene cyclopropane moieties (Scheme 8). [35][36][37] When R in 2 and 3 is changed from H to OMe, the pressure sensitivity of the cycloaddition increases ( Table 4). …”