New routes to highly functionalised compounds from vinylcyclopropanes

Studies towards the development of a novel methodology have been achieved. A Palladium-catalysed [3 + 2] cycloaddition is described herein. Doubly activated vinylcyclopropanes have been ring opened with palladium (0) and the resulting zwitterionic π-allyl palladium species have participated in a nucleophilic addition with activated carbonyl moieties to construct tetrahydrofurans as a mixture of diastereoisomers. The palladium-catalysed [3 + 2] cycloaddition has shown to be successful with ketone moieties activated by an adjacent electron-withdrawing group such as ethyl esters in a range of α-keto esters, and amides in a range of substituted isatins (scheme 1). The reaction boasts good yields and the stereochemical preference of the reaction has shown to be dependent on the choice of reaction solvent. [Illustration omitted.] The reaction has shown to be successful on application to the intramolecular mode to form a bicyclic heterocycle (scheme 2). [Illustration omitted.] The methodology has been successfully incorporated towards the synthesis of the natural product monocerin.