Intramolecular cycloaddition reactions of cis -1,2-dihydrocatechol derivatives incorporating C3-tethered diazoketones, nitrile oxides, and azides: Stereocontrolled routes to enantiomerically pure spiro[5.5]undecanes and related systems

A series of enantiomerically pure cis-1,2-dihydrocatechol derivatives incorporating C3-tethered diazoketone, nitrile oxide, or azide residues has been prepared from the precursor iodide 7 using Negishi cross-coupling reactions. Such derivatives, including diazoketone 12, participate in regio- and stereo-selective intramolecular cycloaddition reactions to give adducts, for example, 15, that are readily elaborated to spiro[5.5]undecanes such as 18.