Bis-Boric Acid-Mediated Regioselective Reductive Aminolysis Of 3,4-Epoxy Alcohols

Readily available epoxides are versatile building blocks in organic synthesis.Due to the intrinsic high ring stain,epoxides can undergo ring opening reactions with a variety of nucleophiles under the catalysis of metal-or organocatalysts,or even under catalyst-free conditions,providing various alcohols bearing a functional moiety on the β-position as the products.In the case of amines as nucleophiles,amino alcohols can be obtained,which are present as a characteristic structure in numerous natural products and pharmaceuticals.On the other side,the reduction of nitroarenes represents one of the most conventional methods to prepare anilines in the industry.In this Master’s thesis,bis-boric acid-mediated regioselective reductive aminolysis of 3,4-epoxy alcohols has been developed,offering new access to preparing amino alcohols in high diastereoselectivity.In comparison to the traditional aminolysis of epoxides,this reaction utilizes nitroarenes directly as the starting materials and thus demonstrates better step-economy.Bis-boric acid has been proven to play a dual role in this reaction,wherein it not only reduces nitroarenes to anilines under the catalysis of 4,4’-bipyridine but also facilitates the hydroxyl-directed stereospecific nucleophilic attack on the C—3 position of 3,4-epoxy alcohols by the in situ generated anilines.