A streamlined approach was developed for accessing 2,3,4-substituted 1-azabicyclo1.1.0butanes from azirines under aza-Darzens-type reaction conditions. The pronounced ring strain in these bicyclic systems enabled distinctive electrophilic transformations via activation of the N-C(3) bond, leading to the formation of substituted azetidines. The relative configurations of the 1-azabicyclo1.1.0butanes were established by 2D NMR, while single-crystal X-ray analysis of the azetidines confirmed their structures and, by analogy, supported the configurational assignments of both these synthesized classes.
Raju et al. (Wed,) studied this question.