Novel dithiane-based molecular systems: Electron transfer-induced fragmentation studies.

摘要

The goal of this research was to design and synthesize dithiane-based molecular systems that are capable of undergoing electron-induced fragmentation by either photo- or electrochemistry.; A laser flash photolysis (LFP) study was carried out on several 1,3-dithiane carbonyl adducts in the presence of a photosensitizer, resulting in our understanding that after formation of the dithiane cation radical, C–C bond scission occurs with the assistance of the anion radical sensitizer.; We then prepared 1,3-dithianes via an experimentally simple and efficient direct transformation of 1,n-alkyl dihalides using carbon disulfide and sodium borohydride. This method provided us with a useful alternative to create more complex dithiane systems.; In our attempts to electrochemically induce fragmentation in dithiane carbonyl adducts, we discovered that adducts carrying alkyl substituents underwent partial dehydration upon electrolysis. This facile elimination prompted us to explore the possibility of using 2-(hydroxymethyl)-1,3-dithiane esters (Dim esters) as electrochemically removable protecting groups for carboxylic acids. The reaction worked precisely as planned, with both simple carboxylic acids and amino acids successfully being protected with the Dim esters, and then removed via electrolysis in excellent yields.; In the search for useful synthons to functionalize dithianes, we synthesized 5,5-bis(hydroxymethyl)-1,3-dithiane, which allowed us to link crown ethers with dithiane through a spiro connection. The use of crowns facilitates our desire to use host/guest complexation chemistry, and combined with our ability to photochemically cleave our systems, enabled us to design molecular tweezers which release their bound guest upon irradiation.; Finally, using the chemical knowledge obtained throughout the course of the research, we developed a dithiane system which actually increases its ability to absorb sunlight as it is exposed to solar irradiation. This unique property could be a very valuable tool in the effort to develop better dermatological protection from damaging UV rays, and if incorporated into a sunscreen formulation, would actually boost its effectiveness as exposure to sunlight increased.