Transformation of three-membered rings

The reaction of 1-arylsulfonylaziridines 217 with dimethylsulfoniumethoxycarbonyl methylide 218 is a fairly general approach for stereoselective synthesis of 1-arylsulfonylazetidines 219 bearing an ethoxycarbonyl functionality (Equation 58) 1995J(P1)2605 . However, the products are obtained in moderate yields. The reaction involves a regioselective transfer of an ethoxycarbonyl-substituted methylene group from the ylide to 1-arylsulfonylaziridines. 

1-Azabicyclo[1.1.0]butanes serve as a precursor for various N-substituted azetidines. A THF solution of 1-azabi-cyclo[1.1.0]butane, obtained from 2,3-dibromopropanamine hydrobromide, yielded azetidine derivatives on treatment with various reagents such as HCl-EtOH, HBr-ClC02Et, Ts20, HC02H (2.7N) HCl-MeOH, or Ac20-HCl 

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