PHOTOCHEMISTRY OF THE PHTHALIMIDE SYSTEM. 23. PHOTOCYCLIZATION OF N-ALKOXYALKYLPHTHALIMIDES WITH FAVORED Δ-HYDROGEN ABSTRACTION: SYNTHESES OF OXAZOLO(4,3-A)ISOINDOLES AND OXAZOLO(4,3-A)ISOINDOLE-1-SPIRO-1′-CYCLOALKANE RING SYSTEMS