Synthesis of 3-thiocyanated chromones via TCCA/NH4SCN-mediated cyclization/thiocyanation of alkynyl aryl ketones

3-Thiocyanated chromones was conveniently synthesized from alkynyl aryl ketones using commercially available, inexpensive trichloroisocyanuric acid (TCCA) as oxidant and NH4SCN as thiocyanato (SCN) source. This metal-free approach is postulated to first in situ generate thiocyanogen chloride (Cl-SCN) from the reaction of TCCA and NH4SCN, followed by a rare efficient electrophilic thiocyano oxyfunctionalization of alkynes enabled by the reactive electrophilic species generated thereof. 3-Thiocyanated chromones were conveniently synthesized from alkynyl aryl ketones using commercially available, inexpensive TCCA as oxidant and NH4SCN as thiocyanato (SCN) source. This metal-free approach is postulated to first in situ generate thiocyanogen chloride (Cl-SCN) from the reaction of TCCA and NH4SCN, followed by a rare efficient electrophilic thiocyano oxyfunctionalization of alkynes enabled by the reactive electrophilic species generated thereof. [Display omitted]