Anisylsulfanylmethylisocyanide (<b>Asmic</b>) is a valuable building block that has been used to access a diverse range of trisubstituted isocyanides. In this work, Asmic was sequentially deprotonated and trapped with esters to prepare oxazoles. An analogous deprotonation-trapping sequence using imidates or nitriles afforded imidazoles. The oxazoles and imidazoles bear an anisylsulfanyl group which serves as an excellent handle for introducing an additional substituent to the heterocycles. We demonstrated a first-in-class sulfur-lithium exchange reaction that generates a lithiated heterocycle which can be trapped with an array of electrophiles. This sulfur-lithium exchange provides a short, efficient method to selectively control all three substituents on oxazoles and imidazoles. We will discuss the scope of the method as well as the discovery of a unique role of borane in activating the heterocycles for lithiation.

Asmic-based synthesis of tri-substituted oxazoles and imidazoles

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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