Electrochemical intramolecular haloheterocyclization reactions using 1,2-dihaloethanes as halogenating reagents

An electrochemical intramolecular haloheterocyclization of N-alkenylamides to prepare 2-oxazolines, 2-thiazolines, 1,3-oxazines and isoxazolines using readily available 1,2-dihaloethanes as halogenating reagents has been developed. [Display omitted] Electrochemistry has a lot of inherent advantages in organic synthesis and many cyclization reactions have been achieved under electrochemical conditions. However, the electrochemical intramolecular haloheterocyclization of N-alkenylamides using bulk and common chemicals such as 1,2-dihaloethanes as halogenating reagents are less studied. Herein, we have developed an electrochemical intramolecular haloheterocyclization of N-alkenylamides to prepare 2-oxazolines, 2-thiazolines, 1,3-oxazines and isoxazolines using readily available 1,2-dihaloethanes as halogenating reagents. This protocol is a convergent strategy integrating several reactions, such as N-alkenylamide chlorooxygenation, chlorosulfuration, bromooxygenation and bromosulfuration. The reaction avoids the use of catalysts, reductants, oxidants, metal salts and iodine reagents, which makes it more sustainable and renewable.