Study On Diazo Compounds Participated Synthetic Reactions

Diazo compounds have attracted chemists' interest for more than one hundred years.However,the diazo compounds people studied always have an eletro-withdrawing group which can stabilize the diazo compounds,those without eletro-withdrawing groups are toxic and highly explosive,and people lack safe methods to study these kinds of diazo compounds.N-Tosylhydrazones,which were found to be able to form diazo compounds in situ,provide a safe and convenient strategy for chemists to study the unstablized diazo compounds.From the other pointview,they also provide more choices to apply carbonyl compounds in organic synthesis.By oxidation of corresponding diazo compounds,a variety of 2,3-diketoesters which were widely utilized in organic synthesis can be easily accessed.In this thesis,N-tosylhydrazones participated X-H(X = C,N,O,S,P)insertion reactions,dipolar cycloaddition reactions and cross-coupling reactions are summarized.In the meanwhile,we conclude some nucleophilic addition reactions involving 2,3-diketoesters.Several new applications of N-tosylhydrazones and 2,3-diketoesters have been developed.Intermolecular N-H insertion reactions of N-tosylhydrazones were disclosed.Subsequently,their applications in the synthesis of azines and oximes were studied.By varying the reaction conditions,the above mentioned products can be obtained respectively in high yields(more than 90%).Highly efficient synthesis of S-alkyl dithiocarbamates was achieved via three component reactions of N-tosylhydrazones,CS2 and amines from which the products were obtained in up to 95%yield.Both the N-H insertion and S-H insertion reaction were realized under metal-free conditions.A series of bromo-substituted novel 1H-pyrazoles,bromo-substituted 3H-pyrazoles were synthesized via metal-free intermolecular cycloaddition reactions of N-tosylhydrazones with gem-dibromoethenes.The products were obtained in high regioselectivity with up to 86%yield.The structure was confirmed via 2D NMR and theoretical calculation.A varirty of novel trifluoromethyl group substituted 3H-pyrazoles were accessed via intramolecular dipolar cycloaddition reactions.Conversion of trifluoromethyl group substituted 3H-pyrazoles to 1H-pyrazoles were investigated subsequently from which N-substituted 1H-pyrazoles and trifluoromethyl group substituted 1H-pyrazoles were obtaind respectively via radical process or[1,5]sigmatropic rearrangement process in up to 90%and 89%yields,respectively.Cu(acac)2-catalyzed Wittig reactions of ketone derived N-tosylhydrazones with aldehydes were first developed which provide a way to synthesis trisubstituted alkenes,the alkenes were formed in up to 71%yield with up to 99%E-selectivity.In order to form trifluoromethyl group substituted alkenes,CuI catalyzed Wittig reactions of aldehyde derived N-tosylhydrazones with 2,2,2-trifluoroacetophenone were shown to be highly effective.Considering that the above methods have some disadvantages including operating cumbersome and highly cost,we successfully developed a one-pot two step method to synthesis trisubstituted alkenes by using N-tosylhydrazones and alcohols as starting materials.Cascade reactions of 2,3-diketoesters with in situ generated enamines were studied,this methodology provides an opportunity to synthesis novel 5-vinyl pyrrole and 4-hydroxy indole derivatives efficiently.Asymmetric aldol reactions of 2,3-diketoesters with cyclic ketones were achieved for the first time by using L-proline as catalyst.The aldol products were formed in up to 92%yield with up to 89:11 d.r.,the major diasterisomers were all formed in 99%ee.Subsequently,benzylic acid rearrangement of the aldol products was studied from which a variety of novel pyrrole-3-one derivatives were obtained in up to 91%yield.It is worth to note that all the pyrrole-3-one derivatives were formed in 99%ee.