Unusual chemo- and stereo-selectivities in the reactions of 1,2-dichlorocyclopropenes with nitrile oxides

Abstract

1,2-Dichloro-3,3-dimethylcyclopropene reacts with a number of nitrile oxides to produce oxazines in moderate to good yield in a reaction which apparently involves an unusual formal 3-centre plus 3-centre cycloaddition of the dipole to an intermediate vinylcarbene. In contrast, 1,2-dichloro-3-chloromethyl-3-methylcyclopropene undergoes a dipolar cycloaddition to produce a 2-oxa-3-azabicyclo[3.1.0]-hex-3-ene in which the 6-chloromethyl substituent occupies the endo-position.