The ene reactions of dimethyl dioxosuccinate (1) and of diethyl dioxosuccinate (2) with olefins give the expected addition products. The reactions of 1 with vinyl ethers or an eneamine provide the cyclopentenones 15 and 16 in a sequence which is consistent with an ene reaction followed by a cyclization. The tin tetrachloride catalyzed conversion of 6 to 17 provides an example of a formal type II ene reaction to give a cyclopentyl ring. However, the stereochemistry of 17 suggests the reaction involves a stepwise ionic process.
Investigation of the mechanisms of ene reactions of carbonyl enophiles by intermolecular and intramolecular hydrogen-deuterium isotope effects: partitioning of reaction intermediates
作者:Zhiguo Song、Peter Beak
DOI:10.1021/ja00178a042
日期:1990.10
concerted mechanism for each reaction. In the ene reactions of 1 with 8 catalyzed by tin tetrachloride and of 1 with acetylium hexachloroantimonate, both the intermolecular and intramolecularisotopeeffects are small, results that are inconsistent with either a stepwise reaction via an equilibrating intermediate or a concerted mechanism. The ene reaction of 2 with acetic anhydride catalyzed by zinc chloride