C-H Activation Study On The Flavanones Catalyzed By Rhodium Carbenoids

This thesis consists of two sections. The first section reviews the metal carbenoids derived from diazo compound, and the classical reaction of metal carbenoids;Diazo compounds as a precursor of free radicals carbene or metal compound carbene are widely used in organic synthesis. Metal carbenoids are widely used due to its high selectivity and reaction diversity. The classical metal carbine reactions include:(1)X-H (including the C-H, O-H, N-H, S-H) insertion reaction; (2) the cyclopropanation reaction of olefin; (3) Ylide reaction; (4) 1,2-migration reaction. The second section is the core of my thesis work, mainly describes the 1,2-migration reaction, C-N bond formation reaction and cyclopropanation reaction of our flavanone diazo catalyzed by rhodium catalyst.Natural product Chamaejasmine represents a unique 3,3"-biflavanones skeleton and chamaejasmine has wide range of physiological activity.In 2005, our group reported the first total synthesis of dl-Chamaejasmine and a series of 3,3"-biflavanones., but the key step coupling reaction has some disadvantages:low yield, separation hydrous and difficult to repeat, so it was urgent target to improve and optimize the key step. The retro synthesis methodology of this thesis was designed to get the 3,3"-biflavanones through the C-H insertion reaction of flavanone diazo catalyzed by rhodium catalyst. During the study of C-H insertion reaction of flavanone diazo, we found specific reaction activity derived from the unique substrate structure of flavanone diazo, then we made a deep research on these reactions, including 1,2-migration reaction, C-N bond formation reaction, cyclopropanation and cyclopropenation reaction.