Gold-catalyzed cycloisomerization of alk-4-yn-1-ones
作者:Volker Belting、Norbert Krause
DOI:10.1039/b819704k
日期:——
Depending on the substitution pattern and the solvent, the gold-catalyzed cyclization of alk-4-yn-1-ones 1 affords different oxygen heterocycles under mild reaction conditions. Alkynones with one substituent at C-3 undergo a 5-exo-dig cycloisomerization to substituted furans 2, whereas a 6-endo-digcyclization to 4H-pyrans 3 is observed with substrates bearing two substituents at C-3. In alcoholic solvents
tethered with a vinyl azide group undergo a Schmidt-hydrolysis sequence to give secondary lactams bearing a ketone side chain. Secondary lactams are obtained in a regioselective manner that is not possible in a conventional Schimdt reaction. In addition to the well-documented C-2 nucleophilicity, the N nucleophilicity of vinyl azide disclosed in this work opens a new direction for reaction invention involving