Stereoselective Synthesis of Tetrasubstituted 2,3-Dihydrofurans by One-Step Cyclization of β-Ketosulfides of Benzothiazole and Aldehydes in Ionic Liquids
摘要:
A stereoselective synthesis of tetrasubstituted 2,3-dihydrofurans was carried out in n-butylpyridinium tetrafluoroborate ([bpy(+)] [BF4-]) as solvent. The reaction proceeds smoothly in one step starting from simple materials such as aldehydes and beta-ketosulfides of benzothiazole. A comparison between several ionic liquids (ILs) is presented, and the role of the benzothiazolyl moiety is discussed. Workup proved to be very easy and recycling of IL possible.