Metal-Free Amidation Of Ethers With N,N-Dibromosulfonamides

Amides are an important class of N-containing compounds in organic chemistry and also potential precursors for the synthesis of numerous natural products, pharmaceuticals, and bioactive polymers. The most prevalent strategy for preparation of amides relies heavily on activated carboxylic acid derivatives or rearrangement reactions induced by a base or acid, which generally involves tedious procedures or needs anhydrous conditions. The conversion of a C-H bond into an amine functionality by nitrene insertion in an intermolecular fashion was discovered by Breslow and co-workers in the early 1980s, and since then several catalytic systems based on iron, cooper, palladium and ruthenium have been also described. However, most of the transition-metals are expensive, high toxicity, which limits the application of an amidation reaction to a certain extent. Therefore, the development of cheap, readily available, low toxicity of transition-metal catalyzed or metal-free amidation reaction conditions is very important.This thesis is divided into three parts, the first chapter reviewed the research progress of metal-catalyzed amidation reactions. Transition-metals catalyst such as copper, iron, ruthenium, and manganese, together with some ligands were usually employed as catalysts. In which the metal-catalyed amidation of C-H bonds is operationally straightforward and provides amides in good to excellent yields for most cases, and inexpensive and readily available reagents were utilized under mild conditions.The second chapter is metal-free amidation of ethers with N,N-dibromosulfonamides. We have developed a new and direct route for the synthesis of amides through the metal-free catalyzed amidation of ethers with N,N-dibromosulfonamides. A series of hemiaminal ethers and imines were prepared with moderate to good yields. This reaction is operationally straightforward, utilizing inexpensive and readily available reagents in the absence of metal-catalysts under mild conditions. This protocol provides a new way for the preparation of natural products and pharmaceutical molecules, containing hemiaminal ethers units.The third chapter is asymmetric Mannich reaction of ?-naphthol derivatives with formaldehyde catalyzed by a Leiws acid and a chiral ligand. Preliminary, results showed that a spirocyclic ring system with a quaternary carbon stereocenter can be constructed with moderate enantioselectivity.