Development Of Novel C-C,C-O Bond Formation Reactions Based On The Activation Of α-C-H Bonds Of Tertiary Amines And In-catalysis

The development of mild, selective and efficient C-C bond formation reactions via carbon-hydrogen bond activation and the use of greener catalysts are an important and long-standing goal in chemistry. Potentially, the synthesis of complex molecules via C-H bond activation could be shorter, simpler, and more atom economical while the use of greener catalysts could lead to greener process, thus generating less waste. Tertiary amines are an important class of organic compounds with versatile biological and physiological activities and widespread in natural and non-natural products.As a Lewis acid, Indium salts are considered to be greener catalysts than most of the traditional Lewis acid because they are nontoxic and compatible with water and air. They can catalyze many kinds of organic reactions. Due to the requirement of environmental concerns, application of indium salts in organic reactions have attracted more and more chemists'interest in recent years.This thesis describes our recent research efforts working on these two topics and the research covered here mainly dealt with the development of reactions via the C-H activation ofα-C-H bonds of tertiary amines and the development of novel C-C,C-O bond formation reactions via In-catalysis.In chapter 1, some of the recent developments of C-H activation ofα-C-H bonds of tertiary amines are summarized which is followed by a general review of the reactions catalyzed by indium salts. In chapter 2, coupling reactions of tertiary amines and siloxyfurans via Cu-catalysis were studied. After examining the activities of various copper salts as catalyst under different oxidant, we found the optimized reaction conditions for this transformation. Using the optimized reaction conditions severalγ-aminoalkyl butenolides were prepared. In addition a possible mechanism was proposed. The use of a relatively cheap copper catalyst in place of expensive and complicated rhodium catalyst could be beneficial for large scale preparations.In chapter 3, Mannich reaction of N-aryl tetrahydroisoquinolines and methyl ketones via Cu-catalyzed was studied. After screening various catalysts and solvents, we found the optimized reaction conditions for this transformation. Under the optimized conditions the scope of the substrates was investigated and a variety of N-aryl tetrahydroisoquinolines were successfully coupled with different methyl ketones.In chapter 4, the intramolecular cyclization of arene-alkene substrates via indium(III) Lewis acids catalysis has been developed. After optimizing the condition of the cyclization reaction, several chromane, tetrahydroquinoline, tetralin derivatives were prepared accordingly. Compared to previous reports, our protocol is advantageous because higher yields of the products can be obtained with inexpensive and environmentally friendly indium catalyst.In chapter 5, an efficient catalytic method for the preparation of tetrasubstituted furans starting from propargylic alcohols and 1,3-dicarbonyl compounds has been developed. After optimizing the condition of the reaction between propargylic alcohols and 1,3-dicarbonyl compounds, the scope of the substrates were investigated and several tetrasubstituted furans were prepared. A possible mechanism was proposed. Our reaction is relatively favorable compared with the reported method in terms of both operational simplicity and the high product yields. Our method does not require the addition of stoichiometric amount of base to effect the cyclization step, and one-step one-pot synthesis of polysubstituted furans is realized. The procedure that we developed not only extended the scope of In-catalysis but also could be complementary to the existing methods for the synthesis of furans.