An extension of our methodology on solid-phase synthesis of 3,4,5-trisubstituted-1,2,4-triazoles under mild conditions has been developed. Firstly, the resin-bound acylhydrazine is reacted with orthoesters to provide ...An extension of our methodology on solid-phase synthesis of 3,4,5-trisubstituted-1,2,4-triazoles under mild conditions has been developed. Firstly, the resin-bound acylhydrazine is reacted with orthoesters to provide resin-bound 1,3,4-oxadiazoles. Secondly, condensation of 1,3,4-oxadiazoles resin with the corresponding arylamines hydrochloride to form the the resin-bound triazoles. 3,4,5-Trisubstituted-1,2,4-triazoles derivatives were obtained from resin-bound acylhydrazines in several steps providing 78% - 87% overall yields and excellent purity. The advantages of this method include straightforward operation and high yield and purity of the products.展开更多
The synthesis of 1,3,5-substituted-1,2,4-triazoles from α-imino-3-pyridine formic acid,acetamidine and anisole hydrazine as a model reaction in this paper and the synthesis mechanism of 1,3,5-substituted-1,2,4-triazo...The synthesis of 1,3,5-substituted-1,2,4-triazoles from α-imino-3-pyridine formic acid,acetamidine and anisole hydrazine as a model reaction in this paper and the synthesis mechanism of 1,3,5-substituted-1,2,4-triazole compounds from carboxylic acids,amidines and hydrazines have been first investigated with the B3 LYP/6-311＋＋G＊＊ method.According to the potential energy profile,it can be predicted that the course of the reaction consists of five reactions containing six elementary reactions.The α-imino-3-pyridine formic acid and acetamidine form first an intermediate product through a dehydration reaction; the intermediate product further combines with hydrogen ion to form a positive ion; the positive ion reacts with anisole hydrazine by a dehydration reaction to form another positive ion; then,followed by two isomerization reactions,the final reaction with the acetate ion（Ac-） produces the final product.The research results reveal the laws of synthesis reaction of 1,3,5-substituted-1,2,4-triazoles by the carboxylic acids,amidines,hydrazines and their derivatives on theoretical level.It provides the systemic theoretical basis for the synthesis,development and application of 1,3,5-substituted-1,2,4-triazole compounds.展开更多
A copper-catalyzed three-component reaction of diazo compounds,nitriles,and azodicarboxylates to construct 2,3-dihydro-1,2,4-triazoles is reported.Key to the success is the utilization of azodicarboxylates to trap the...A copper-catalyzed three-component reaction of diazo compounds,nitriles,and azodicarboxylates to construct 2,3-dihydro-1,2,4-triazoles is reported.Key to the success is the utilization of azodicarboxylates to trap the in-situ formed nitrile ylides from diazo compounds by[3+2]-cycloaddition.Both the acceptor-only and donor-acceptor diazo compounds are all tolerated to the strategy.The synthetic value of this protocol is illustrated by gram-scale synthesis and valuable transformation of the obtained 2,3-dihydro-1,2,4-triazoles.展开更多
A series of new 2,5-disubstituted-l,3,4-oxadiazole and 1,2,4-triazole derivatives were synthesized by hetero- cyclization of acid hydrazide I and thiosemicarbazide derivative 2. Furthermore, the acyclic C-nucleoside a...A series of new 2,5-disubstituted-l,3,4-oxadiazole and 1,2,4-triazole derivatives were synthesized by hetero- cyclization of acid hydrazide I and thiosemicarbazide derivative 2. Furthermore, the acyclic C-nucleoside analogs were prepared by cyclization of their corresponding sugar hydrazones by reaction with acetic anhydride. The antimicrobial activity of the prepared compounds was evaluated and some of the synthesized compounds revealed good activities against fungi.展开更多
A simple metal and additive-free approach for the assembly of 5-trifluoromethyl-1,2,4-triazoles via only heatinginduced decarboxylative cyclization of readily available trifluoroacetimidohydrazides andα-oxocarboxylic...A simple metal and additive-free approach for the assembly of 5-trifluoromethyl-1,2,4-triazoles via only heatinginduced decarboxylative cyclization of readily available trifluoroacetimidohydrazides andα-oxocarboxylic acids has been developed.In this protocol,the rarely reported tetrahedral carboxylic acids intermediate could be in-situ generated and undergo subsequent decarboxylation to afford the target heterocycle products.展开更多
文摘An extension of our methodology on solid-phase synthesis of 3,4,5-trisubstituted-1,2,4-triazoles under mild conditions has been developed. Firstly, the resin-bound acylhydrazine is reacted with orthoesters to provide resin-bound 1,3,4-oxadiazoles. Secondly, condensation of 1,3,4-oxadiazoles resin with the corresponding arylamines hydrochloride to form the the resin-bound triazoles. 3,4,5-Trisubstituted-1,2,4-triazoles derivatives were obtained from resin-bound acylhydrazines in several steps providing 78% - 87% overall yields and excellent purity. The advantages of this method include straightforward operation and high yield and purity of the products.
基金supported by the National Natural Science Foundation of China(No.51102114)
文摘The synthesis of 1,3,5-substituted-1,2,4-triazoles from α-imino-3-pyridine formic acid,acetamidine and anisole hydrazine as a model reaction in this paper and the synthesis mechanism of 1,3,5-substituted-1,2,4-triazole compounds from carboxylic acids,amidines and hydrazines have been first investigated with the B3 LYP/6-311＋＋G＊＊ method.According to the potential energy profile,it can be predicted that the course of the reaction consists of five reactions containing six elementary reactions.The α-imino-3-pyridine formic acid and acetamidine form first an intermediate product through a dehydration reaction; the intermediate product further combines with hydrogen ion to form a positive ion; the positive ion reacts with anisole hydrazine by a dehydration reaction to form another positive ion; then,followed by two isomerization reactions,the final reaction with the acetate ion（Ac-） produces the final product.The research results reveal the laws of synthesis reaction of 1,3,5-substituted-1,2,4-triazoles by the carboxylic acids,amidines,hydrazines and their derivatives on theoretical level.It provides the systemic theoretical basis for the synthesis,development and application of 1,3,5-substituted-1,2,4-triazole compounds.
基金the National Natural Science Foundation of China(Nos.21971001 and 21702001)for financial support.
文摘A copper-catalyzed three-component reaction of diazo compounds,nitriles,and azodicarboxylates to construct 2,3-dihydro-1,2,4-triazoles is reported.Key to the success is the utilization of azodicarboxylates to trap the in-situ formed nitrile ylides from diazo compounds by[3+2]-cycloaddition.Both the acceptor-only and donor-acceptor diazo compounds are all tolerated to the strategy.The synthetic value of this protocol is illustrated by gram-scale synthesis and valuable transformation of the obtained 2,3-dihydro-1,2,4-triazoles.
文摘A series of new 2,5-disubstituted-l,3,4-oxadiazole and 1,2,4-triazole derivatives were synthesized by hetero- cyclization of acid hydrazide I and thiosemicarbazide derivative 2. Furthermore, the acyclic C-nucleoside analogs were prepared by cyclization of their corresponding sugar hydrazones by reaction with acetic anhydride. The antimicrobial activity of the prepared compounds was evaluated and some of the synthesized compounds revealed good activities against fungi.
基金support from the Natural Science Foundation of Zhejiang Province(No.LY19B020016)the K.C.Wong Education Foundation(No.GJTD-2020-08).
文摘A simple metal and additive-free approach for the assembly of 5-trifluoromethyl-1,2,4-triazoles via only heatinginduced decarboxylative cyclization of readily available trifluoroacetimidohydrazides andα-oxocarboxylic acids has been developed.In this protocol,the rarely reported tetrahedral carboxylic acids intermediate could be in-situ generated and undergo subsequent decarboxylation to afford the target heterocycle products.
