Liashuk O. [2+2] and [3+2] cycloadditions of unsaturated boronates

The dissertation work is devoted to the study of underexplored cycloaddition reactions of unsaturated boronates (in particular, substituted vinyl and ethynyl boronates) resulting in new saturated or monounsaturated (hetero)cyclic building blocks for the medical chemistry purposes. A method of azomethine ylide cycloaddition to substituted vinyl boronates giving pyrrolidine-3-boronates was developed. Classical variations of this approach – using catalytic amounts of trifluoroacetic acid under normal conditions or equivalent amounts of lithium fluoride in refluxing acetonitrile – were shown to be only limitedly suitable for substituted substrates. Due to the insufficient obtained results, an extensive optimization study of the protocol was carried out. According to the results of this optimization, the optimal reaction conditions for the cycloaddition of vinyl boronates and azomethine ylide were found. In particular, the use of lithium fluoride as a promoter and DMSO as a solvent under heating to 110 °C allowed significantly increase the yield and purity of the tested compound.