Simple and Efficient Preparation of Dihydropyrans and Spiroketals Using the Intramolecular Silyl Modified Sakurai (isms) Reaction

Substituted tetrahydropyrans, spiroethers and spiroketals can be prepared in a single step using the ISMS reaction between the bis-silylated reagent 7b and aldehydes (acetals), ketones (ketals) and ortholactones respectively. This simple methodology was applied to the rapid synthesis of a pheromone containing a [4,5]-spiroketal unit.