The Studies Of P-toluenesufonylhydrazide For The Selective Reduction Of Chalcones And The Synthesis Of 2-arylchromans

This thesis focused on the studies of p-toluenesufonylhydrazide for the selective reduction of chalcones, the synthesis of 2-arylchromans, and Palladium-catalyzed C-H ortho-arylation with an aminoacetic acid bidentate directing group, which is divided two parts as follow:Part one: The studies of p-toluenesufonylhydrazide for the selective reduction of chalcones and the synthesis of 2-arylchromansChalcone is an important class of organic synthetic precursor compounds and key intermediates, which are widely used in medicine, pesticides, spices and other fields.Chalcone has two functional groups and the carbon-carbon double bond conjugated with a carbonyl group; therefore, it has the chemical characters including the olefin,the ketone, and the conjugated diene. This part focus on the study of the selective conjugate reduction of chalcones by using p-toluenesufonylhydrazide as a hydride donor. This protocol is inexpensive without the use of any noble transition metal, and is efficient being applicable to a wide range of substrates. Besides,p-toluenesufonylhydrazide mediated reductive coupling cyclization of 2-hydroxyl dihydrochalcones is described. This is an unprecedented protocol and an extremely efficient method for the synthesis of 2-arylchromans in good to excellent yields from commercially available, cheap starting materials. Furthermore, the operational simplicity of the process and the high functional group tolerance are remarkable.Part two: The studies on Palladium-catalyzed C-H ortho-arylation with an aminoacetic acid bidentate directing groupTransition-metal-catalyzed functionalization of carbon-hydrogen bonds is a topic of recent intense interest in the past two decades. Transition metal catalyzed chelation-assisted C-H bond activation is currently in widespread use in such transformations. In this part, we have developed a novel protocol for the palladium-catalyzed ortho-arylation of benzoic acids using an aminoacetic acid as double chelated group. The method allows only mono-arylation of benzoyl aminoacetic acid substrates, shows excellent functional group tolerance and provides an efficient method for the synthetic of 2-aryl benzyl acids with up to 93% yield. The aminoacetic acid auxiliary is effectively detached under mild conditions.