Preparation and Crystal Structure of Two Bicyclo[1.1.0]butan-2-ones: A Hybrid Oxyallyl−Cyclopropanone Motif

The first X-ray crystal structures of two different bicyclo[1.1.0]butanones show a very long transannular bond of 1.69 Å and a large carbonyl pyramidal distortion of 0.26 Å out of the plane of the three carbons. These features are those expected of molecules with a hybrid cyclopropanone−oxyallyl structure, and these structures differ markedly from those of the parent bicyclo[1.1.0]butane skeleton.