Photosynthesis of Heteropolycyclic Diquinolones Twofold Photodehydrohalogenation Reaction of Benzo[1,2-b:4,5-b']dithiophene- and Dithieno[3,2-b:2',3'-d]thiophenedicarboxanilides

Abstract

Heteropolycyclic diquinolones; benzo[l.Z-b:4>-b']dithieno[2',3'-c':2",3"c"]-5,13-N,N'-dimethyldiquinoline-6,14-dione(9) and dithienoI3.2-b:2',3'd]thienyl[2",3"-c:2",3"-c']-5,lO-N~-dimethyldiquinoline-6,9-dione(17) are prepared by twofold photochemical dehydrohalogenation reaction of corresponding benzodithiophene-and dithienothiophenedicarboxanilides; 3,7dichloro-NR-dimethylbenzo[l ,2-b;4J-b']dithiophene-2,6-dicarboxanilie (8) and 3~-dichloro-N~-dimethyldi~eno[3.Z-b:2',3'-dJthiophene-2,6-dicarboxanilide (16).The products of onefold photochemical dehydrohalogenation reaction, anilidoquinolones; 9-chloro-lO-N'-methylanilidobenzo[l~-b:45-b']dithieno[2,3- el-5-N-methylquinolin-6-one (10) and 10-chloro-9-N'-methy~anilidodithieno[3,2b:2',3'-d]thieny1[2",3"-~']-5-N-methylquinolin-6-one (18) were also isolated to prove the mechanism of the reaction.Recently we reporkdl on the applicability of photochemical dehydrohalogenation reactions of some heteropolycyclic dicarboxanilides in producing anilidoquinolones.Photochemical dehydrogenation reaction of anilidoquinolones to produce multicondensed diquinolones didn't occur.In our previous papers we reported on the usefulness of photochemical dehydrocyclisation reaction for preparing quinolones condensed with heterocyclic nuclei: furoquinolones,2 furo-bis-quinolones,~ benzofurophenanthridones and benwthienophenanthridonesP This reaction was examined and applied to aromatic and heteroarornatic anilides5-9 but the yields of the corresponding heterocyclic quinolons were not high.It was shown that the more applicable reaction to produce heterocyclic quinolones, was photochemical dehydrohalogenation reaction which was first reported by Terashima and coworkers.10The authors examined photochemical dehydrohalogenation reaction on a few different heterocyclic amide systems where the halogen atom was situated in the position 2 of the amino part of heterocyclic nuclei or in the same position of the acidic part of the heterocyclic nuclei.The authors noticed that the reaction of photochemical dehydrohalogenation was facilitated when the halogen atom CHO CH=CHCOOH coa- CHO CH=CHCOOHScheme 1 (to be continued)