Sodium tetrachloroaurate(III) dihydrate-catalyzed efficient synthesis of 1,5-benzodiazepine and quinoxaline derivatives

Abstract

Both 1,5-benzodiazepine and quinoxaline derivatives are important heterocycles in pharmaceuticals. We describe an efficient and clean method for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones catalyzed by sodium tetrachloroaurate(III) dihydrate under mild conditions. The catalyst was shown to be equally effective for the synthesis of quinoxalines from o-phenylenediamine and α-bromo ketones under the similar reaction conditions. This method produced good yields.

Synthesis of New [1,5]-Benzodiazepine Derivatives Catalyzed by Various Aliphatic Acids

“…The wide range of applications of benzodiazepines has attracted many researchers and various methods are known for their synthesis under different conditions. Among these methods condensation of o-phenelendiamine and ketones in the presence of a variety of catalysts like p-toluenesulfonic acid (Pasha and Jayashankara, 2006), silica sulfuric acid (Ahmad and Ali, 2007), p-nitrobenzoic acid (Varala, et al, 2008), sodium tetrachloroaurate dehydrate (Shi, et al, 2010), AlCl 3 (More, et al, 2011) polyethylene glycol (Konda, et al, 2011). Unfortunately these methods involve many limitations like tedious work up procedure, producing undesired washes, applications of expensive catalyst and reagents, long reaction times, unsatisfactory yield, high purification cast.In last few years, there has been growing interest in the use of organic catalyst that can proceed and accomplish the reaction under aerobic atmosphere, other notable advantages are, commercially less expensive (Scheme 1)…”

Rapid and Efficient Synthesis of 2,3-Dihydro-1H-1,5-Benzodiazepines Catalyzed by Chloroacetic Acid Screened among Various Aliphatic Acids

“…The wide range of applications of benzodiazepines has attracted many researchers and various methods are known for their synthesis using different catalysts under different conditions. These methods include condensation of o-phenylenediamine and ketones in the presence of a variety of catalysts like p-toluenesulfonic acid 8 , silica sulfuric acid 9 , p-nitro benzoic acid 10 , sodium tetrachloroaurate(III) dehydrate 11 , AlCl 3 12 , polyethylene glycol 13 . But these methods involve many limitations like tedious work up procedure, producing undesired washes, applications of expensive catalyst and reagents, long reaction times, unsatisfactory yield; require separation of the catalyst from the product and formation of side products.…”