Notes- Naphthoquinone Chemistry. 6H, 11H-Benzo[f]pyrido[a]benzimidazole-6,-11-dione

Heterocyclic Quinones from 2,3-Dichloro-1,4-naphthoquinone.

“…Mosby and Boyle (60) found that under the conditions of the above methods the angular quinone XLIV rather than the linear XLIII was formed. According to Mosby (59) the linear isomer XLIII is obtained by refluxing 2-chloro-3-ethoxy-l,4-naphthoquinone [prepared from 2,3-DCNQ, ethanol and sodium acetate (26) ] with 2-aminopyridine in ethylene glycol dimethyl ether. A 34% yield of XLIII as golden-tan needles of m.p.…”

“…Evidence that the compound obtained by Mosby from 2-chloro-3-ethoxy-l,4-naphthoquinone has the structure XLIII is provided by the reduction of this compound to the known 1,2,3,4-tetrahydronaphth-[2',3'-4,5]imidazo[l,2-a]pyridine-6,ll-dione (58) and by the failure to obtain a phenazine derivative by treatment with o-phenylenediamine (59).…”

One-Pot Synthesis of Naphth[2',3':3,5]imidazo[1,2-α]pyridine-6,11-doines from 2-Amino-3-chloro-1,4-naphthoquinone and Pyridine Derivatives

“…Dioxonaphthalimidazopyridine derivatives such as naphth- [2',3':4,5]imidazo [1,2-a]pyridine-6,11-dione and 9-methylnaphth [1',2':4,5]imidazo [1,2-a]pyridine-5,6-dione are interesting chemical entities both as a chromophoric 1 and a pharmacological agent for treating diseases related to venous insufficiency and/or inflammatory edema. 2 Most of the early methods developed for their synthesis are reactions of 2chloro-3-hydroxy-, 2-chloro-3-ethoxy-and 2-chloro-3-acetoxy-1,4-naphthoquinones with 2-aminopyridines, 3 thermolysis of 3-azido-2-chloro-1,4-naphthoquinone in excess of pyridine 1 and condensation reaction of 2,3-dichloro-1,4naphthoquinones with 2-aminopyridine using phase transfer catalyst. 4 Recently, Pérez-Pérez and co-workers reported 5 that the reactions of 6-amino-1-benzyluracil 1 with N-bromosuccinimide (NBS) in pyridine at 80 ºC afforded 6-amino-1benzyl-5-bromouracil 2 and 1-benzyl-1H,3H-pyrido[2,1f]purine-2,4-dione 4 via intermediate dibromo compound 3 (Scheme 1).…”