A rapid and simple amine-catalyzed microwave-assisted isomerization of maleamides into fumaramides

Imidazolium ylides from a conjugate addition–proton transfer route and their cycloaddition reactions

“…Interconversion of maleate to the more stable fumarate can be mediated by initial reversible conjugate addition of the dihydroimidazole to the electron-deficient maleate alkene. 8 The dipolarophile-derived portion of the isolated adducts clearly shows the C-6 and C-7 ester groups to be trans, i.e. the alkene has fumarate geometry when it acts as dipolarophile, suggesting the conjugate addition is rate-determining.…”

Diels–Alder reaction of fused pyran-2-ones with ethyl vinyl ether

“…We found that such conditions (analogous to those used previously) [31,32] were not adequate to achieve quantitative conversion into the products 5; indeed, the only way to achieve this was to apply higher reaction temperatures (140-180°C). However, in order to reach temperatures above 120°C while keeping the pressure below the upper limit [as the boiling point of the neat ethyl vinyl ether (2) is rather low (33°C)], it was necessary to add some appropriate additives to decrease the vapor pressure, such as ionic liquids (e.g., [bmim]BF 4 ) or n-butanol (which, due to the easier isolation of the products, proved to be preferable) [47][48][49][50].…”

Modulation of Reactivities of Dienophiles for DielsAlder Reactions via Complexation of α,β‐Unsaturated Chelating Amides

“…was dissolved in MeCN (1.50 ml) in a microwave tube. After addition of piperidine (12.0 ml, 0.12 mmol, 8 mol-%), the mixture was heated under microwave at 1208 with 150 W for 45 min [18]. The mixture was dissolved in CH 2 Cl 2 (50 ml) and washed with sat.…”