External Base-free Electrophilic Diynylation of Thiols with Diynyl Benziodoxolone

In this study, external base-free electrophilic diynylation of thiols to 1,3-butadiynyl sulfide, an important structural motif in organic synthesis, chemical biology, and materials science using triisopropylsilyl diynyl benziodoxolone at room temperature has been developed. Various thiols, such as cysteine and thioglucopyranose derivatives and captopril, were converted into the corresponding 1,3-butadiynyl sulfides. Control experiments and a computational study were performed to investigate the reaction mechanism. The resulting 1,3-butadiynyl sulfides were further derivatized to thiobitriazole via double azide-alkyne cycloaddition and to cyclobutene via [2 + 2] cycloaddition.