Asymmetric Cycloetherification of in Situ GeneratedCyanohydrins through the Concomitant Construction of Three ChiralCarbon Centers

The organocatalytic enantio- and diastereoselective cycloetherification of in situ generated cyanohydrins through the concomitant construction of three chiral carbon centers is reported. This protocol facilitates the concise synthesis of optically active tetrahydropyran derivatives, which are ubiquitous scaffolds found in various bioactive compounds, through the simultaneous construction of multiple bonds and stereogenic centers, including tetrasubstituted chiral carbons. The resulting products also contain multiple synthetically important functional groups, which expand their possible usefulness as chiral building blocks.