Unsymmetrically-Substituted 5,12-dihydrodibenzo[b,f][1,4]diazocine-6,11-dione Scaffold—A Useful Tool for Bioactive Molecules Design

Unsymmetrically N-substituted and N,N’-disubstituted 5,12-dihydrodibenzo [b,f][1,4]diazocine-6,11-diones were synthesized in the new protocol. The desired modifications of the dibenzodiazocine scaffold were introduced at the stages of proper selection of building blocks as well as post-cyclization modifications with alkylation or acylation agents, expanding the structural diversity and possible applications of synthesized molecules. The extension of developed method resulted in the synthesis of novel: tricyclic 5,10-dihydrobenzo[b]thieno[3,4-f][1,4]diazocine-4,11-dione scaffold and fused pentacyclic framework possessing two benzodiazocine rings within its structure. Additionally, the unprecedented rearrangement of 5,12-dihydrodibenzo[b,f][1,4]diazocine-6,11-diones to 2-(2-aminophenyl)isoindoline-1,3-diones was observed under the basic conditions in the presence of sodium hydride for secondary dilactams. The structures of nine synthesized products have been established by single-crystal X-ray diffraction analysis. Detailed crystallographic analysis of the investigated tri- and pentacyclic systems has shed more light on their structural features. One cell line derived from non-cancerous cells (EUFA30—human fibroblasts) and three tumor cells (U87—human primary glioblastoma, HeLa—cervix adenocarcinoma, BICR18—laryngeal squamous cell carcinoma) were used to determine the cytotoxic effect of the newly synthesized compounds. Although these compounds showed a relatively weak cytotoxic effect, the framework obtained for 5,12-dihydrodibenzo[b,f][1,4]diazocine-6,11-dione could serve as a convenient privilege structure for the design and development of novel bioactive molecules suitable for drug design, development and optimization programs.