摘要
A facile 3-step synthetic approach to 3-halo-4-substituted-l,5-dihydro-4H-1,2,4-triazolme-5-thiones （la--lk） from corresponding unhalogenated 8a---8i was developed based on the strategy of retro-Michael addition, with the key steps being regioselective S-alkylation of compounds 8a-8i with ethyl 3-iodopropionate（12c） and alkaline cleavage of the propionate protecting group via retro-Michael addition. The synthetic approach was characterized by simplicity of operation and wide substrate scope.
A facile 3-step synthetic approach to 3-halo-4-substituted-l,5-dihydro-4H-1,2,4-triazolme-5-thiones （la--lk） from corresponding unhalogenated 8a---8i was developed based on the strategy of retro-Michael addition, with the key steps being regioselective S-alkylation of compounds 8a-8i with ethyl 3-iodopropionate（12c） and alkaline cleavage of the propionate protecting group via retro-Michael addition. The synthetic approach was characterized by simplicity of operation and wide substrate scope.
基金
Supported by the Key Projects of Tianjin Science and Technology Support Plan, China（No.16YFZCSY00910）, the Tianjin Natural Science Foundation, China（Nos. 12JCYBJC18800, 13JCQNJC 13700） and the Shandong Natural Science Foundation, China（No.ZR2015BM028）.
