Compendium of Cycloaddition Reactions under High Pressure

High-Pressure Cycloaddition Reactions in the Synthesis of Biologically Relevant Heterocycles

“…The high-pressure conditions at room temperature are beneficial in particular, since furan cycloadducts are generally susceptible to thermal retrofragmentation yielding back to reagents or decomposition. Literature survey reveals that a huge number of furan cycloadditions were carried out under high pressure [4]. Another advantage of high pressure is the use of no catalyst for the most of cycloadditions.…”

“…By applying such reaction conditions, many organic reactions are efficiently promoted under milder conditions with no need for a metallic catalyst and/or high temperatures. Until today, a number of cycloadditions were carried out under high pressure, including synthesis of various heterocycles [4]. For these reactions, employment of high pressure is highly beneficial in acceleration of reaction, as cycloadditions exhibit a large negative volume of activation (ΔV ≠ ).…”

Ultra High Pressure as a Green and Promising Tool in Glycochemistry

“…In sugar-related reactions with UHP, cycloadditions are one of the most studied of the last decade [29]. The helpful effect of the pressure in the kinetic of the reaction, as well as the gain of regioand diastereoselectivity in comparison with thermal ones is known since the end of the 70's [30].…”

Short, Enantioselective Total Synthesis of Chatancin

“…With four-step access to an intermediate containing all of the requisite carbons of 1, we were in a position to test the first key C À C bond-forming reaction, a pyrone/alkene cycloaddition; [17,18] elegant synthetic work directed toward the transtaganolide and basiliolide diterpenes served as inspiration. [19] Ultimately it was discovered that heating a toluene solution of the methoxycarbonylated pyrone for 4 days at 100 8C smoothly elicited a [4+2] cycloaddition in high yield (90 %) and without the need for high dilution.…”

“…Notably, hydroxypyrone 10 could not be coaxed into a productive cycloaddition under either thermal or highpressure conditions (entry 1) and pyrone triflate 11 afforded only decarboxylated diene 20 when heated (entry 2). [17] Decarboxylation was also observed for the successful ester substrate, but could be minimized by judicious choice of solvent and temperature. In toluene at 80 8C, the initial [4+2] reaction did not proceed at an appreciable rate, and at 120 8C, substantial decarboxylation was observed.…”