New Strategies for Intramolecular Annulations: Intramolecular Additions of Silyloxycyclopropane-Derived Anions; Application to Hydrindenone Syntheses

as an extension to our work on intramolecular annulations via silyloxycyclopropane derived anions, we have investigated the chemistry of cyclopentyl cyclopropane systems, 6-9, in an effort to prepare stereospecifically functionalized hydrindenones. the intramolecular closures of the cyclopropane-derived anions were less stereoselective and more complicated than the corresponding cyclohexyl systems. nevertheless, modest yields of isomeric hydrinenones such as 20 and 21 were obtained as well as several products derived from a prototropic shift to form the cyclopentanone enolates. these latter products possessed the 5,5-pentalenone systems, 22 and 23.