Green synthesis of some new thiopyrano[2,3-<i>d</i>][1,3]thiazoles using lemon juice and their antibacterial activity

A simple green method has been developed for the synthesis of a series of new 3-phenyl-6-(substituted)-thiopyrano[2,3-<i>d</i>]thiazole-2,5,7(6H)-triones, 6-cyano-2-oxo-3-phenyl-thiopyrano[2,3-<i>d</i>]thiazoles, 3-phenyl-3,5,5a,11b-tetrahydro-2H,6H-chromeno-[4′,3′:4,5]thiopyrano[2,3-d]thiazole-2,6-dione and 5-amino-6-cyano-2-oxo-3-phenyl-3,7-dihydro-2H-thiopyrano[2,3-<i>d</i>]thiazoles <i>via hetero</i>-Diels–Alder reaction by conventional method and green method using lemon juice as natural acid. The structure of all the newly synthesized compounds was interpreted by elemental analyses and spectral data. The synthesized compounds were evaluated for their <i>in vitro</i> antibacterial activity against some pathogenic bacteria. This study is a platform for the future design of more potent antimicrobial agents.本研究开发了一种简便绿色合成方法，可通过常规方法与以柠檬汁作为天然酸的绿色方法，经杂原子狄尔斯-阿尔德（hetero-Diels–Alder）反应，合成一系列新型化合物，包括3-苯基-6-(取代基)-噻喃并[2,3-d]噻唑-2,5,7(6H)-三酮、6-氰基-2-氧代-3-苯基噻喃并[2,3-d]噻唑、3-苯基-3,5,5a,11b-四氢-2H,6H-色烯并[4′,3′:4,5]噻喃并[2,3-d]噻唑-2,6-二酮以及5-氨基-6-氰基-2-氧代-3-苯基-3,7-二氢-2H-噻喃并[2,3-d]噻唑。所有新合成化合物的结构均通过元素分析与光谱数据进行表征。本研究还对所合成化合物开展了针对若干致病菌的体外（in vitro）抗菌活性评价。该项研究可为未来设计更高效的抗菌剂搭建研究平台。