A Highly Stereospecific Claisen–Sakurai Approach to Densely Functionalized Cyclopentenols

The formation of highly substituted cyclopentenols was developed using a Claisen–Sakurai reaction. Both elements of the reaction can be performed in a one-pot sequence that provides the corresponding cyclized products in high stereoselectivity. The stereochemical outcome is defined by a combination of Claisen stereospecificity and stereoelectronic effects in the Sakurai cyclization that promotes reactivity via an anti-SE′ antiperiplanar transition state. This was determined by examination of the product stereochemistry and through detailed DFT analysis.