The Regioselective Addition Of Nucleophiles To α, β-Unsaturated N-Acylbenzoriazoles

The regioselective addition ofα,β-unsaturated carbonyl compounds with nucleophiles is very important in organic synthesis.The dissertation studied the addition reactions of several nucleophiles toα,β-unsaturated N-acylbenzotriazloles with the emphasis on the regioselectivity. The whole dissertation can be divided into two parts:In partâ… ,the regioselective 1,2-or 1,4-addition of phenthiol and indole toα,β-unsaturated N-acylbenzotriazoles was investigated respectively.Firstly,thiophenols were used as S-nucleophile and it was found the regioselectivity of the addition was influenced significantly by the reaction conditions:With silica gel as the catalyst,the 1,2-addition and 1,4-addition took place concurrently and the the bis-addition products were obtained;while catalyzed by ZnCl₂/triethylamine only 1,2-addition occurred and no 1,4-addition products were observed.Subsequent study was focused on the regioselective addition of indoles toα,β-unsaturated N-acylbenzotriazoles.Catalyzed by samarium triiodie,the regioselctive 1,4-addition of indoles(Fridel-Crafts alkylation) with their 3-position proceeded smoothly to afford a variety of new 3-substituted indoles;under basic condition,the regioselective 1,4-addtion of indoles took place with their 1-position and N-substiuted indole derivatives were obtained albeit in low yields.In both cases,the 1,2-addition of indoles with either the 3- or 1-position(Fridel-Creafts acylation) was not observed.It could be concluded from the investigation that the theory of hard-soft acid-base can be used to explain the regioselective addition reaction of nuchelophiles toα,β-unsaturated N-acylbenzotriazoles.The more nucleophilic phenthiol anion as a hard-base prefered to attacking the carbonyl ofα,β-unsaturated N-acylbenzotriazoles and underwent 1,2-addition;while the 1-position or 3-position of indoles were soft-bases,which attacked theβ-carbon ofα,β-unsaturated N-acylbenzotriazoles preferably and the 1,4-addition was observed.In partâ…¡,we focuses on the construction of heterocycles using the bis-addition of arylhydrazines toα,β-unsaturated N-acylbenzotriazols.In the presence of triethylamine,the bis-addition of arylhydrazines toα,β-unsaturated N-acylbenzotriazoles proceeded in a highly regioselective way and only 2-aryl-substituted pyrazolidin-3-ones were obtained in moderated to good yields,which is contrast with results obtained hitherto form aryhydrazines and otherα,β-unsaturated carbonyl compounds.