Benign Catalysis and Expansion of Cyclobenzoins
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Abstract
Cyclobenzoins are a fledgling class of macrocycles first reported by the Miljanić group in 2015. Since the first reports, several modifications to the original two compounds, cyclotribenzoin and cyclotetrabenzoin, have been reported, but no developments on the production have been reported. Whether this is due to the use of sodium cyanide as a catalyst or the small substrate scope, this thesis aims to improve on both limitations. The first issue, the cyanide catalyst, presented an opportunity to develop a new method to synthesize cyclotetrabenzoin. After testing a series of N-heterocyclic carbene catalysts, a suitable alternative was determined. Initial results indicated a substantial drop in yield, but optimizing conditions brought the production from the N-heterocyclic carbene conditions into line with the cyanide-catalyzed conditions. Concerning the substrate scope, initial experiments suggested that the general poor solubility of the aromatic dialdehyde materials in the aqueous conditions prevented their use as cyclobenzoin precursors. Leveraging the newly developed N-heterocyclic carbenes, particularly the ability to utilize organic solvents, two completely novel cyclobenzoins were prepared and characterized.