Catalytic Asymmetric Cycloaddition of Ketenes and Nitroso Compounds

Significance

Dochnahl and Fu describe a catalytic asymmetric [2+2] cycloaddition of ketenes and nitrosoarenes using the nucleophilic catalyst 1. This high-yielding reaction afforded enantioenriched 1,2-oxazetidin-3-ones with good to excellent enantiomeric excess and could be performed on a large scale with equal efficiency. The four-membered heterocycles were converted into several synthetically useful compounds including the 1,2-diol 2 and α-hydroxycarboxylic acid 3.