Aza-Dihydroquinoxaline

To 100 ml 97% H2SO4 cooled in an ice bath was added portionwise 2-amino-5-chloropyridine (0.2 mol) and the resulting mixture heated to 55 °C. Thereafter 13.5 ml 70% HNO3 was added drop wise over 2 hours and the solution heated one hour at 55-60 °C. The mixture was poured into ice water and neutralized with 200 ml 40% NaOH. A yellow precipitate that formed was isolated, washed with with water, dried, and the product obtained in 56% yield. H-NMR data supplied. 

To 100 ml 37% HCl was added portionwise SnC (0.2 mole) and the mixture slowly added to the product from Step 1 (0.050 mol). The mixture refluxed for 30 minutes. 

The produet from Step 2 (0.28 mmol) was added to 2 ml 2M HCl containing oxalic acid (0.33 mmol), refluxed 2 hours, and cooled to ambient temperature. The product was isolated as a brown solid in 23% yield, mp 250°C. H-NMR data supplied. 

Diamines used in Step 3 for preparing of 6-, 8-aza and 6,8-diaza, (I), (II), (III), respectively, are listed below  

(N-oxy)-Aza derivatives were prepared by the author and others (1) in the current invention by reacting the product of Step 3 with 3-chloro-perbenzoic acid as illustrated in Eq. 1 and summarized below  

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