OXIDATIVE REACTIONS OF AZINES. 6. LACTAMIZATION OF 4-ARYL- AND 4-PHENETHENYL-SUBSTITUTED 1,2,3,6-TETRAHYDROPYRIDINES AND DIHYDROXYLATION OF 4-ARYL-1,2,5,6-TETRAHYDROPYRID-2-ONES USING POTASSIUM PERMANGANATE