Asymmetric 1,3-dipolar cycloadditions of chiral carboxyloyl nitrile oxides to cycloalkenes

Asymmetric 1,3-dipolar cycloadditions of chiral carboxyloyl nitrile oxides derived from (2R)-bornane-10,2-sultam, (1R)-8-phenylmenthol, N,N-dicyclohexyl-10-sulfamoyl-(2R)-isoborneol, and 7,7-dimethylnorbornane-(1S,2R)-oxazolidinone to four cycloalkenes, leading to the corresponding 2-isoxazolines in both moderate yields and diastereoselectivities, are presented. All cycloadducts were converted into the corresponding alcohols, which were used for the determination of enantiomeric purity via chiral gas chromatography. In the case of the six-membered ring cycloadduct, the absolute configuration was determined by X-ray analysis.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide

3a,4,5,6,7,7a-Hexahydro-1,2-benzisoxazole-3-carboxylic acid (2′R)-N-bornane-10′,2′-sultam imideC18H26O4N2S[α]D23=-105 (c 0.59, CHCl3)Absolute configuration: (2R)