Functionalized Homocubanes: Oxidative Deiodination of Homocubyl Iodide. Synthesis of 4-Mesyloxy-, 4-Tosyloxy-, and 4-Chloro-1-bromopentacyclo[4.3.0.02,5.03,8.04,7]nonan-9-one Ethylene Acetal from the Corresponding 4-Iodo-1-bromohomocubyl with Hypervalent Iodine