Direct Formation of α-Dione blocks from o-Benzoquinone Cycloadditions and their Value in the Synthesis of Fused Quinoxalines, 1,10-Phenanthrolines and Pteridines - Warrener, Ronald N; Johnston, Martin R; Schultz, Austin C; Golic, Mirta; Houghton, Mark A; Gunter, Maxwell J (Synlett, 1998)