Studies On Reactivity Of Bifunctional Cyano Compounds In Organic Synthetic Chemistry

Transformations and reactivity of functional groups are the basis for organic reactions and syntheses in organic chemistry,all organic reactions are relevant to the transformations of functional groups.Compared to monofunctional cyano compounds,bifunctional cyano compounds have another functional group that can together serve in conversions and reactions;thus bifunctional cyano compounds possess more reaction potentials and higher research values.?-Keto nitriles and cyanoepoxides these two kinds of bifunctional cyano compounds were designed and synthesized in this thesis,and some researches on their reactivities of bifunctional cyano groups in the presence of acids are as follows:(1)A convenient and expeditious strategy to synthesize difluoroboron complexes of ?-keto amides has been developed from ?-keto nitriles and BF3·OEt2.BF3·OEt2 serves as both a BF2 source and a Lewis acid catalyst in the synthetic strategy.The difluoroboron complexes can be further converted into ?-keto amides,which play great roles in organic synthesis by treatment with sodium acetate.The strategy features advantages such as a wide substrate scope,non-metal catalysis,and easy operation.Some of the difluoroboron complexes display good fluorescence properties in the solid state and potential applications in solid-state luminescent materials.(2)Arylacetic acid derivatives were readily synthesized from 3-aryloxirane-2-carbonitriles with amines,alcohols,or water in the presence of boron trifluoride.The reaction undergoes an acid-promoted Meinwald rearrangement,producing arylacetyl cyanides,followed by an addition-elimination process with nitrogen or oxygen-containing nucleophiles.The reaction features advantages of microwave irradiation acceleration,short reaction time,metal-free synthesis,readily accessible starting materials,and wide substrate scope.(3)A safe and convenient synthetic method to anti-?-(N-arylamino)-?-hydroxynitriles from 3-aryloxirane-2-carbonitriles and anilines was developed under the catalysis of BF3·OEt2 in ethanol.In this method,BF3·OEt2 first reacts with ethanol to produce the true catalyst of super acid H[B(OEt)F3],followed by an acid-catalyzed regio-and diastereoselective ring-opening of oxirane-2-carbonitriles with anilines,generating anti-?-(N-arylamino)-?-hydroxynitriles.The method features advantages of nonmetal catalysis,short reaction time,easy to operation,and environmental solvent.(4)A convenient synthetic method to indoles,especially 2-arylindoles,from anilines and cyanoepoxides was developed under the catalysis of BF3·OEt2 or AlCl3 in the presence of TFE.The reaction involves a tandem reaction of regiospecific ring-opening of cyanoepoxides with anilines,elimination of cyanide,intramolecular aromatic electrophilic substitution,and water elimination.The Lewis acid reacted with TFE generating H[B(OR)F3]is an efficient catalyst.The current method features advantages of readily accessible starting materials,wide substrate scope,transition-metal-free environment,and regiospecific synthesis of substituted indoles.(5)A convenient,metal-free,and organic acid-base promoted synthetic method to 3-arylindoles from vicinal aryloxiranecarbonitriles and arylhydrazine hydrochlorides has been developed.In the reaction,the organic acid catalyzes a tandem nucleophilic ring-opening reaction of aryloxiranecarbonitriles and arylhydrazine hydrochlorides and Fischer indolization.The organic base triethylamine not only plays a crucial role in the final elimination step in the Fischer indole synthesis,affording 3-arylindoles regiospecifically but also serves as acid binding agent to react with arylhydrazine hydrochloride and release arylhydrazine participating in the next reaction.The reaction features advantages of microwave acceleration,non-metal participating,short reaction time,organic acid-base co-catalysis,and broad substrate scope.