Sarut Jianrattanasawat
Western Michigan
Incorporation of heterocyclic moieties, such as an oxazole, can offer improved solubility, rigidity, and ability to accept hydrogen-bonds. Recently, our group showed synthesis of oxazoles through a two-step procedure starting from an epoxide. First, an epoxide was opened in the presence of a Lewis acid to form a b-amino alcohol. This was followed by an oxidation using manganese dioxide. This method tolerates a variety of epoxide substrates, as well as a wide range of substituents at the 2-position of the oxazole. When other oxidizing agents were explored, such as N-bromosuccinimide (NBS) or 1,3-dibromo-5,5-dimethylhydantoin (DBDMH), we were able to chemoselectively oxidize the b-amino alcohol to oxazoline and 4-bromo-oxazoline, respectively. Structurally rigid compounds such as 1,10-phenanthroline offers insight into the oxidation mechanism. When NBS and DBDMH were used to oxidize 1,10-phenanthrolineaminoalcohols, only oxazoles were isolated.