Catalytic Asymmetric Synthesis of Allenoates by Isomerization of Alkynoates

Significance

The authors report an enantio­selective isomerization of various alkynoates to the corresponding allenoates catalyzed by a chiral Brønsted base. The products were obtained in moderate to high yields and good enantioselectivities at relatively low catalyst loadings. Although most of the products were inseparable from un­reacted starting material, the obtained mixtures were successfully used in further transformations, such as cycloadditions or lactonizations. These reactions proceeded with good chirality transfer and allowed the reisolation of the unreacted alkyne.