Study On Benzothieno [3,2-d] Thiazole Synthesis From Sulfur Powder As Sulfur Source

Nitrogen-containing heterocyclic compounds are widely found in nature.thiophene and thiazole,whose derivatives have also shown good development prospects in the field of photovoltaic materials,are the basic structural units of many drug molecules.Based on these findings,in the process of continuous development of heterocyclic chemistry,methods for synthesizing nitrogen-containing and sulfur-containing compounds are endless.But It has always been a central issue for researchers to seek a greener,simpler,and more efficient synthesis.At the same time,the low-cost,non-toxic and long-term stable elemental sulfur,which has a good coupling promoting effect on the formation of nitrogen-containing heterocyclic rings and sulfur-containing heterocyclic rings,has many functions.There are the goals for us to explore and synthesize bioactive bi-heterocyclic compounds.In this parper,We carried out research on the synthesis of benzothieno[3,2-d]thiazole derivatives using elemental sulfur as the sulfur source without the use of transition metals.Three-component self-assembled bis-heteroannulation reaction for one-pot synthesis of benzothieno[3,2-d]thiazole derivatives from ketoxime esters,methyl nitrogen heterocycle and elemental sulfur has been developed.The reaction was performed with cesium carbonate as an additive,dimethyl sulfoxide as solvent to achieve ordered oxidative functionalization of multiple inactive C-H bonds.This method didn't use copper,iron,ruthenium and other transition metals to activate the N-O bond of ketoxime esters,and the elemental sulfur can not only be used as a viable sulfur source,but also an effective redox medium.In this method,there are many advantages that provide a simple way to synthesize the benzothieno[3,2-d]thiazole skeleton with high yield,mild reaction conditions,wide adaptability of the substrates and good functional group tolerance.