Studies On Br(?)nsted Acid Promoted Asymmetric Hydrogenation And Oxidative Dearomatization

The organic compounds containing nitrogen or oxygen atoms are important skeleton structure for the synthesis of pharmaceuticals, natural products, and functional materials. Amines and alcohols as well as nitrogen-and oxygen-containing heterocyclic compounds are essential intermediates in organic synthesis. Transition-metal-catalyzed asymmetric hydrogenation of ketones and ketimines is one of the most direct and efficient method for the preparation of chiral alcohols and amines. Meanwhile, transition-metal-catalyzed dearomatization is a feasible way for the transformation and functionalization of aromatic or hetero-aromatic compounds under mild reaction conditions. This thesis describes palladium-catalyzed asymmetric hydrogenation of unactivated ketones and ketimines as well as ruthenium-catalyzed oxidative dearomatization of N-Boc indoles by using Br(?)nsted acid as a promoter.In the present study,a homogeneous Pd-catalyzed asymmetric hydrogenation of unactivated ketones1was successfully developed using Pd(OCOCF3)2/(R)-C4-TunePhos/salicylic acid as a catalyst system with up to88%ee. The Pd-catalyzed asymmetric hydrogenation of unactivated ketones1can be achieved by using salicylic acid (10mol%) as the promoter. Furthermore, a new method was provided for the preparation of chiral alcohols2,especially for the synthesis of alcohols with bulky substituents.In this work, a homogeneous Pd-catalyzed asymmetric hydrogenation of unactivated imines3was successfully developed using Pd(OCOCF3)2/(R)-C4-TunePhos/D-DTTA as a catalyst system with up to95%ee. The Pd-catalyzed asymmetric hydrogenation of unactivated imines3a-s can be achieved by using D-DTTA (20mol%) as the promoter. Furthermore, the above mentioned approach provides a facile access to chiral cyclic amines containing1,2,3,4-tetrahydronanphthyl-1-amine and3,4-dihydro-2H-chromen-4-amine frameworks, which represent an interesting structural motif found frequently in various bioactive molecules and natural products.Ru-catalyzed oxidative dearomatization of N-Boc indoles5was also successfully developed for the synthesis of2-substituted-3-oxyindolines6and7by using lert-butyl hydroperoxide (TBHP) as an oxidant. The reaction has many advantages such as mild reaction conditions, high atom economy and friendly environment.