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An efficient synthesis is described for hexabromoanthracenes 3 and 4 by direct bromination of 9,10-dibromoanthrecene 2. Whereas base-induced elimination of hexabromide 3 with t-BuOK gave 2,3,9,10-tetrabromoanthracene 5, the reaction of hexabromide 4 with DBU afforded 1,3,9,10-tetrabromoanthracene 6 as the sole product. Tetrabromide 5 was also obtained by aromatization of 1,4-dinitroxy-2,3,9,10-tetrabromo-1,2,3,4-tetrahydroanthracene 17. Efficient and convenient synthetic routes are described for the preparation of dinotroxy 17, dimethoxy 23, and dihydroxides 18 and 19 with silver-induced substitution of hexabromides 3 and 4. The hydroxy compounds 19 and 18 were converted to diepoxide 20 and monoepoxide 21, respectively, with sodium methoxide. Base-promoted aromatization of dimethoxide 23 afforded dibromomonomethoxides 26 and 27. Bromoanthracenes and isomeric arene oxides constitute valuable precursors for the preparation of functionalized substituted anthracene derivatives that are difficult to prepare by other routes.

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We report the synthesis of bromoindenoquinolines (15a-f) by Friedlander reactions in low yields (13-50%) and the conversion of the corresponding phenyl-substituted indenoquinoline derivatives 16-21 in high yields (80-96%) by Suzuki coupling reactions. To explore the structure-activity relationship (SAR), their inhibition potentials to inhibit acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and human carbonic anhydrase cyctosolic (hCA I and II) enzymes were determined. Monophenyl (16-18) indenoquinolines significantly inhibited the AChE and BChE enzymes in ranges of IC 37-57 nM and 84-93 nM, respectively, compared with their starting materials 15a-c and reference compounds (galanthamine and tacrine). On the other hand, these novel arylated indenoquinoline-based derivatives were effective inhibitors of the BChE, hCA I and II, BChE and AChE enzymes with K values in the range of 37 ± 2.04 to 88640 ± 1990 nM for AChE, 120.94 ± 37.06 to 1150.95 ± 304.48 nM for hCA I, 267.58 ± 98.05 to 1568.16 ± 438.67 nM for hCA II, and 84 ± 3.86 to 144120 ± 2910 nM for BChE. As a result, monophenyl indenoquinolines 16-18 may have promising anti-Alzheimer drug potential and 3,8-dibromoindenoquinoline amine (15f) can be novel hCA I and hCA II enzyme inhibitors.

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Ten new isoxazoline derivatives were synthesized from the reactions of benzonorbornadiene and homonorbornadiene derivatives with nitrile oxides formed from benzaldehyde and 4‐substituted benzaldehyde. Two new pyridazine derivatives were also synthesized from the reaction of the homonorbornadiene derivatives with 3,6‐di (2‐pyridyl)‐s‐tetrazine. It was seen that all cycloaddition reactions were realized as exo selectivity. Finally, γ‐Gauche effect in the isoxazoline derivatives was discussed.