Aryne-Mediated Synthesis of Oxygen Heterocycles and Application to Cysteine-Selective Trapping

The use of arynes as the highly reactive intermediates in organic synthesis has attracted substantial attention. Particularly, the introduction of ortho-(trimethylsilyl)aryl triflates as easily activatable aryne precursors led to growing activity in this field. Most reactions using these aryne precursors proceed through the addition of nucleophiles to arynes and the subsequent trapping with electrophiles to give the multisubstituted arenes with structural diversity and complexity. Based on our studies, this review highlights the insertion of arynes, generated from ortho-(trimethylsilyl)aryl triflates, into C=O π-bond of formamides. Initially, the representative examples for formal [2+2] cycloaddition of arynes with the carbon–heteroatom double bond or the heteroatom–heteroatom double bond are shown. Next, the studies on the insertion of arynes into the N−C and C=O bonds of amide group including our three-component coupling reaction leading to oxygen heterocycles are summarized. The SN2’ reaction of tricyclic oxygen heterocycles, obtained by three-component coupling reaction, was studied by using carbon and sulfur nucleophiles. The SN2’ reaction was expanded to four-component coupling reaction. Finally, the application of tricyclic oxygen heterocycles to cysteine-selective trapping is described. CONTENTS