Selenocysteinyl electrophiles efficiently promote the formation of coumarin and quinolinone cores by 6-endo-dig cyclization

Abstract

Efficient methods have been disclosed for the construction of nitrogen and oxygen containing heterocyclic systems attached to selenocysteine or selenoglutathione. An inorganic oxidant (K₂S₂O₈) or a mild Lewis acid (CuBr₂) was employed for the generation of selanyl electrophiles that were further trapped with phenyl propiolates, methyl 2-(phenylethynyl)benzoate, N-phenyl propiolamides and 2-(phenylethynyl)benzamide thus providing the respective coumarins, isocoumarins, quinolin-2-ones and isoquinolin-2-ones via 6-endo-dig cyclization. The use of visible light resulted in divergent reactivity providing triple bond addition products or spirocyclic compounds bearing selenocysteine moieties.