摘要
We present here a series of low-energy visible-light-induced metal-free C-I, C-S, and C-Se cross-coupling reactions for the formation of iodo-vinyl-thiocyanates (IVTs) and iodo-vinyl-selenocyanates (IVSs) using alkynes, iodine and ammonium thiocyanate (NH4SCN)/potassium selenocyanate (KSeCN) in the presence of oxygen at room temperature. Upon photo-irradiation, iodine, molecular oxygen, and NH4SCN synergistically generate iodine radical, singlet oxygen (1O2), and (SCN)-S-center dot/(SeCN)-Se-center dot radicals, respectively, and selectively react with alkyne to form stereoselective E-configured IVTs and IVSs. Iodine plays a significant role as I2 acts as a photoactive species, undergoing homolytic cleavage to form iodine radicals, while singlet oxygen is produced via energy transfer (ET), and thiocyanate/selenocyanate radicals via single-electron transfer (SET) process. Moreover, green chemistry metrics and Eco-Scale evaluations highlight that the current stereoselective oxidative C-I, C-S, and C-Se coupling protocol aligns well with sustainable principles, establishing it as a viable and environmentally benign approach to organic synthesis.