Catalytic asymmetric cycloaddition of ketenes and nitroso compounds: enantioselective synthesis of alpha-hydroxycarboxylic acid derivatives.

The appropriate choice of chiral catalyst and starting materials leads to the synthesis of 1,2-oxazetidin-3-ones by cycloadditions of ketenes with nitroso compounds with very good regioselectivity and enantioselectivity. In addition to serving as potentially bioactive target molecules, the products can be transformed into other important classes of compounds, such as alpha-hydroxycarboxylic acid derivatives.