Organic Azides in Heterocyclic Synthesis. Part 31. Thermolytic Ring Closure Reactions of 4-Azido-3-phenylsulfanyl- and 4-Azido-3-phenylsulfonyl-2-quinolones to 12H-Quinolino[3,4-b][1,4]benzothiazin-6(5H)-ones.