Dibenzo quinazoline

A radical mechanism is also proposed when 5,6-diiodouracil is irradiated in benzene to lead to a mixture of 5-iodo-6-phenyluracil, 5,6-diphenyluracil, 6-bi-phenyl-2-yl-uracil, and finally dibenzoquinazoline [74JCS(P 1)2649]. The dibenzo-quinazoline is also formed by photocycliza-tion of 6-o-biphenyloxyuracil (74JA315) (Scheme 155). 

Dibenzofuran, I- and 2-hydroxy-chlorination, 59, 251 chloro-dehydroxylation, 59, 251 Dibenzofuran, methoxy-, dimethoxy-, bromination, 59, 252 Dibenzo[/, /i]quinazoline-2,4-dione, 1,3-dimethyl-, 55, 226... 

Cinnoline 1 (benzo[c]pyridazine), phthalazine 2 (benzo[ /]pyridazin), quinazoline 3 (benzo[benzene-fused diazines. Of the dibenzo-annulated systems, only phenazine 5 (dibenzopyrazine) will be discussed. 

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