Synthesis, investigation of spectroscopic and catalytic properties of novel neutral boronate esters

Boronate esters, an important group of boron chemistry, were synthesized by using the Dean-Stark system as a result of the esterification of boronic acids with different cis-diols under suitable conditions. Boronate esters synthesized for different purposes are widely preferred in synthetic and industrial chemistry today due to their unique physical and chemical properties, different chemical structures, important spectroscopic properties, and high catalytic activities. In the literature search, there are few studies examining the catalytic activities of boronate esters in the reactions of CO2 as organocatalyst and synthesis of five-membered ring carbonates from epoxides. In this study, firstly, the synthesis of eight boronate esters with different structures was carried out. Then, the structures of these compounds were elucidated by NMR (1H, 13C and 11B) spectroscopy, FT-IR spectroscopy, UV-Vis spectroscopy, LC-MS/MS spectrometry, elemental analysis and melting point methods. The catalytic activities of the synthesised boronate esters (1-8) as organocatalysts in the synthesis of 4-chloromethyl-1,3-dioxalan-2-one by cyclo-addition reaction of CO2 to epichlorhydrin were investigated. In addition, after determining the most active catalyst in the conversion of CO2 to cyclic carbonate, optimisation studies such as epoxide, base, time, temperature, pressure, amount and atmospheric pressure were carried out to determine the most ideal system conditions.