Quinone imine dimethylacetals

Scheme 24 Synthesis of quinone imine dimethylacetals and quinone imines...

During a synthesis of quinone imine precursors to the Dynemicins, Myers and co-workers100 encountered problems with the lability of the dimethyl acetal function in 56,1 [Scheme 1.56] whilst removing the robust phenolic methyl group using sodium ethanethiolate in hot DMF, However prior conversion of the free hydroxy function in the substrate to the magnesium salt 56.2 by reaction with ethylmagnesium bromide afforded protection for the dimethylacetal under the strenuous conditions of nucleophilic demethylation. 

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