Study On Syntheses Of P-and Si-chiral Organic Compounds Through Transition Metal Catalyzed Desymmetric Reactions

In recent years,transition metal-catalyzed asymmetric C-H bond functionalization provides a highly efficient and atomically economical method for the synthesis of C-stereogenic chiral compounds.The bonding radius of Si and P atoms are longer and these heteroatomic bonds are easier to polarize when compared to C,that makes silicon and phosphorus chiral center easily to racemization;In addition,it is not easy for an asymmetric catalytic system to telorate the harsh react condition for the activation of C-H bond.Therefore,the synthesis of silicon and phosphorus stereogenic chiral compounds based on the asymmetric C-H functionalization is a good strategy but still faces great challenges.This thesis focuses on the aspects of Ir-catalyzed intramolecular direct dehydrosilylation and palladium-catalyzed C-H functionalization of prochiral Si or P stereogenic compounds as follows: 1.A new asymmetric catalytic approach that palladium-catalyzed intramolecular direct C-H arylation of prochiral o-bromoaryl phosphine oxides to corresponding P-stereogenic phosphloe oxides was developed in goo yield.The enantioselectivities were closely associated with the specific structures of substrates,which indicated by the ee of the products that ranged from 4% to 94%.In addition,the ee values of the products can be increased through recrystal processes.This research provided a simple and straightforward procedure for the synthesis of P-stereogenic phosphole oxides.Break through the limitation that previous chiral phosphloe oxides had to be resolved on chiral preparation chromatography.2.A series of silicon-bridged acative hydrosilane substrates were synthesized from commercially available silanols.These substrates were converted to structurally diverse five-membered and six-membered cyclic organosilicon compounds containing disiloxane fragments through Ir-catalyzed intramelocular direct C-H silylation.This highly efficient and simple catalytic system can be applied to a borad scope of substrates.Further research confirmed that the two non-equivalent and modifiable silicon substituents in the target product molecules can be selectively reacted.The outstanding advantages of the structure of these compounds make them useful intermediates in the synthesis of complex compounds.3.Silicon stereogenic chiral organosilicon compounds were constructed successfully using palladium catalyzed desymmetry C-H olefination strategy.The pyridine substituted prochiral tetra-substituted silane and various active olefins were used as materials,monoprotected chiral amino acids were used as ligands,enabling the generation of relevant nitrogen-containing silicon-stereogenic architectures.The catalytic system exhibits good functional group compatibility for differently substituted olefins.And the ortho positions of one of the aryl groups were monofunctionalized with high regio-and stereo-selectivity,gave the Si-stereogenic chiral silane with up to 91% ee.