Methods for the Direct Synthesis of Benzoxazoles from Halogenated Nitriles in Alcoholic Solvents

Two complementary approaches for the direct synthesis of 2-dichloro- and 2-trichlorobenzoxazoles from 2-aminophenols and halogenated nitriles are reported. A green, noncatalyzed method was shown to proceed in an alcoholic solvent without the addition of exogenous acid or base. This method provides a clean and robust synthesis of these important heterocycles, which contain a key functional group handle at the 2-position. A complementary platinum multifaceted catalysis approach was also developed in which the metal can catalyzes multiple mechanistically distinct processes. This method allows for an improved use of the metal catalyst vs stepwise protocols and provides increased flexibility in the choice of reaction conditions