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 silyloxy cyclopropane derived anions, we have investigated the chemistry of cyc lopentyl cyclopropane systems, 6-9, in an effort to prepare stereospec ifically functionalized hydrindenones. The intramolecular closures of the cyclopropane-derived anions were less stereoselective and more com plicated than the corresponding cyclohexyl systems. Nevertheless, mode st 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-penta lenone systems, 22 and 23.