Iodine catalysed unprecedented synthesis of ferrocenated thiols and bis-dithianes: Chemoselectivity and smart phone based metal sensing application

Acetalisation of (2-Formyl-1-chlorovinyl)ferrocene with various acyclic and cyclic thiols leads to the synthesis of a variety of ferrocenated mono-, bis- and di-thianes. The series of ferrocene-substituted thiols is synthesized for the first time. The excellent yield of both the thiols and dithianes compounds was obtained under mild reaction conditions in the catalytic presence of molecular iodine. Also, the chemoselective acetalisation of (2-Formyl-1-chlorovinyl)ferrocene, 2-(1,3-dioxan-2-yl)-1-ferrocenylethanone and 2-(1,3-dioxolan-2-y1)-1-ferrocenylethanone towards 1,2- and 1,3-dithiols shows formation of different products. It is also noticed that the transthioacetalisation of 1,3-O,O acetal or 1,2-O,O acetal is dominant over acetalisation of ketones. The mono/dithiane compounds show the promising applications in the optical sensing of Hg²⁺ at remarkably low concentrations.