Fredrik Barnå: Expanding the aryne toolbox: Studies of aryne regioselectivity and precursor post-functionalisation

Abstract

This thesis explores aryne chemistry in two directions, the post-functionalisation of Kobayashi's precursor to prepare novel aryne precursors, and the study of the regioselectivity of aryne capture reactions. The goal was to extend the understanding of aryne regioselectivity, and to open up new avenues for future applications of aryne chemistry.

The crystal structures of several distally borylated Kobayashi's precursors are presented (Paper I). After that, the thesis covers the interaction between the arynes resulting from distally borylated Kobayashi precursors and their boron, demonstrating the unprecedented regioselectivity of capture reactions with these arynes (Paper II). Distally borylated Kobayashi's precursor was converted to an iodonium salt to prepare the first chemoselective formal benzdiyne precursor (Paper III). An iodonium-based aryne precursor was installed in 2,1,3-benzothiadiazole to prepare the novel heteroaryne 4,5-benzothiadiazolyne (Paper IV). Lastly, methods for the optimisation of aryne and cycloalkyne geometries were benchmarked (Paper V). It was found that PBEh-3c offered an excellent performance-to-cost ratio. The largest ever library of aryne and cycloalkyne geometries was prepared. The library was then analysed in the first extensive study of structure-distortion relationships of substituted arynes and cycloalkynes (Paper VI).