Ring-opening Of Aziridines Promoted By Silica Gel And Synthesis Of New Chiral Catalysts

Aziridines represent an important three membered ring system as building blocks in synthetic chemistry and are widely applied for preparation and transformation of N-containing compounds with multi-functional groups.1,2-diamine could be obtained by nucleophilic attack of azo reagent at aziridines, which will be further transformed to the bioligocally active diamino acid for chemical and pharmaceutical industry. Under current developed methods, the 1,2-diamine compounds are mostly obtained by nucleophilic ring opening of aziridines with azides in the presence of Lewis acid or base. However, those acid and basic reagents are relatively expensive for industry application and the metallic pollution fails to meet the rules of the green chemistry. In this paper, we developed a convenient and cheap method for nucleophilic ring opening of aziridines. Under solvent free conditions, the 1, 2-diamino compounds were obtained by ring opening of aziridines with azide promoted by silica gel. All the reactions were finished in 8-50 hours with yield up to 98%.Organic small molecular catalysis represents one of the most promising branches in the field of asymmetric synthetic chemistry. Complementary to the well developed metal complex catalyst, the organic small molecular catalyst also takes some advantages over them. They are more environmentally friendly, more easily available and steady, and easier to be recycled. However, the application of organic catalysis was hampered by lack of catalyst species and developed reactions, and more novel and effective catalysts are desired to be developed in this field. In this paper, we pay our attention to the natural chiral pool--(1R)-(+)-camphor, and four kinds of new chiral organic small-molecular catalysts were synthesized based on the camphor skeleton. They are chiral thiourea, bis (trifluorosulfamide) chiral phosphoric acid, tetraaminophosphonium respectively. Their structures were identified by 1H-NMR, 13C-NMR and HRMS. These three compounds are all new compounds and have not been reported in literature. They have the potential to be highly active and highly enantioselective chiral catalysts.