Synthesis of ubiquinone and menaquinone analogues by oxidative demethylation of alkenylhydroquinone ethers with argentic oxide or ceric ammonium nitrat

Bis[4-(4-pyridyl)pyridinium] (4-carboxypyridine-2,6-dicarboxylato-κ3O2,N,O6)(pyridine-2,4,6-tricarboxylato-κ3O2,N,O6)ferrate(III) trihydrate

“…Pyridine-2,4,6-tricarboxylic acid (H 3 ptc) was synthesized by oxidization of pyridine-2,4,6-trimethyl with potassium permanganate according to a literature (Syper et al, 1980).A mixture of H 3 ptc (0.110 g, 0.05 mmol), FeCl 2 .6H 2 O (0.126 g, 0.10 mmol), 4,4′-bpy (0.156 g, 0.10 mmol), 16 ml H 2 O and seven drops of triethylamine were loaded into a 23 ml Teflon-lined stainless autoclave, which was heated up to 120 °C, at which temperature the reactor was held for 3 days, and then cooled to room temperature. The reaction yielded brown block crystals of (I) in a yield of 10.32% based on …”

[KDy(Hptc)3(H3ptc)]n·2n(Hbipy)·5n(H2O), a Layered Coordination Polymer Containing DyO6N3 Tri-Capped Trigonal Prisms (H3ptc = Pyridine 2,4,6-Tricarboxylic Acid, C8H5NO6; Bipy = 2,2'-Bipyridine, C10H8N2)

“…The nominal pyridine 2,4,6-tricarboxylic acid (H 3 ptc) starting material was prepared by oxidizing 2,4,6-trimethyl pyridine with KMnO 4 solution, as described by Syper et al [11]. This evidently generated a potassium salt: A 0.5-mmol solution was prepared by heating 0.11 g of the solid product in 10.0 mL water in a 50-mL round bottom flask.…”

Silylation–desilylation of quinones and their derivatives

“…The protection of the highly reactive hydroquinone function as a silyl ether, against destructive conditions, during multi-stage syntheses of several quinonoid compounds, followed by synthetic elaboration and oxidation, is an important synthetic strategy for the preparation of complex quinones. These series of reactions are particularly useful and are a common procedure in the synthesis of naturally occurring quinones, such as ubiquinone 22 and anthracycline antibiotics exhibiting high antitumor activity 23 as well as other man-made quinonic products. 24 Moreover, owing to the enhanced hydrolytic stability 25 of some silyl ethers, e.g.…”