A new synthetic method of 3-acyltetronic acid derivatives and its application to the synthesis of isoaspertetronin a (isogregatin A)

A new synthetic method of 3-acyltetronic acid derivatives from the corresponding 3-bromo compound via lithiation with n-BuLi followed either by acylation with acid chloride or better by first reacting with aldehyde and then subsequent oxidation with active MnO₂ is described. A revised structure $\text{10}$ for aspertetronin A(gregatin A) was presented based on the synthesis of the proposed structure $\text{8}$ and spectral comparison of a model compound $\text{12}$ with the natural product.