Catalytic cyclopropanation of methylenecyclobutanes using ethyl nitrodiazoacetate. Synthesis of spirohexane amino acids

The reaction of ethyl nitrodiazoacetate with a series of methylenecyclobutanes was studied and both [1+2]- and [2+3]-cycloaddition pathways were observed depending on olefin structure. Amino acids of a spirohexane type were synthesized from methylenecyclobutanes by a three-step synthesis.