Bismuth‐promoted platinum catalysts were tested for the oxidative coupling of 2‐ and 4‐substituted 1‐naphthols at different temperatures and ambient pressure. The principal final products are the 3,3′‐substituted 1,1′‐binaphthalenylidene‐4,4′‐diones and the 4,4′‐substituted 2,2′‐binaphthalenylidene‐1,1′‐diones, respectively. Hydrogen peroxide was used as the oxidant. Only naphthols with electron‐donating substituents reacted. The corresponding binaphthalenyl diols can be considered as reaction intermediates. Yields of up to 99 % were obtained from 2‐methyl‐1‐naphthol as the starting material within 20 minutes. Probably for steric reasons, the diol is the final product obtained from 2‐ethyl‐1‐naphthol. For 4‐methoxy‐1‐naphthol the outcome is determined by the reaction temperature. At 25 °C the expected 1,1′‐dione is the major product, whereas at 60 °C 1′‐hydroxy‐4′‐methoxy‐2,2′‐binaphthalenyl‐1,4‐dione is formed; the loss of one methoxy unit and the preservation of the hydroxy group can be explained by the competitive cleavage of one of the two OMe bonds at higher temperature. Unpromoted platinum and a range of other metallic catalysts, including gold and Raney nickel, were also found to be active. The products obtained are brightly colored solids that could be used as dyes. The method described is truly catalytic and environmentally benign. The potential of the technique justifies further research to expand on the applicability of this novel method.

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A series of 25 new benzothiazole–urea–quinoline hybrid compounds were synthesized successfully via a three-step synthetic sequence involving an amidation coupling reaction as a critical step. The structures of the synthesized compounds were confirmed by routine spectroscopic tools (1H and 13C NMR and IR) and by mass spectrometry (HRMS). In vitro evaluation of these hybrid compounds for their antitubercular inhibitory activity against the Mycobacterium tuberculosis H37Rv pMSp12::GPF bioreporter strain was undertaken. Of the 25 tested compounds, 17 exhibited promising anti-TB activities of less than 62.5 µM (MIC90). Specifically, 13 compounds (6b, 6g, 6i–j, 6l, 6o–p, 6r–t, and 6x–y) showed promising activity with MIC90 values in the range of 1–10 µM, while compound 6u, being the most active, exhibited sub-micromolar activity (0.968 µM) in the CAS assay. In addition, minimal cytotoxicity against the HepG2 cell line (cell viability above 75%) in 11 of the 17 compounds, at their respective MIC90 concentrations, was observed, with 6u exhibiting 100% cell viability. The hybridization of the quinoline, urea, and benzothiazole scaffolds demonstrated a synergistic relationship because the activities of resultant hybrids were vastly improved compared to the individual entities. In silico ADME predictions showed that the majority of these compounds have drug-like properties and are less likely to potentially cause cardiotoxicity (QPlogHERG > −5). The results obtained in this study indicate that the majority of the synthesized compounds could serve as valuable starting points for future optimizations as new antimycobacterial agents.

Using H2O2 as the oxidant, 1‐naphthols with electron‐donating groups at the 2‐ and 4‐positions couple oxidatively over a carbon‐supported platinum catalyst to 3,3′‐substituted 1,1′‐binaphthalenylidene‐4,4′‐diones and 4,4′‐substituted 2,2′‐binaphthalenylidene‐1,1′‐diones, respectively. The binaphthalenyl diols are the intermediates. The selectivity to individual products is influenced by the reaction temperature (room temp. or reflux) and by the solvent used. Under reflux, complete conversions are obtained within 40 min. At room temp. high diol yields can be obtained, e.g. 96 % from 2‐methyl‐1‐naphthol in MeOH. Under reflux the reaction proceeds always further to the diones (at least to some extent), and THF is a promising solvent for the selective one‐pot two‐step oxidation of 1‐naphthols to the diones (e.g. 81 % from 4‐methoxy‐1‐naphthol). In most other solvents (reflux) naphthoquinones are observed as byproducts. In an attempt to optimize the yield of menadione, 30.5 % was obtained in boiling MeNO2.

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