Abstract Tandem mass spectrometry has been applied to investigate the behaviour of bis- captodative (cd) substituted cyclopropanes NC (SR) CCH 2 C (SR) CN [1, R= CH 3; 2, R= tBu and 3, R= C 6 H 5] upon electron impact (EI) and flash-vacuum pyrolysis (FVP) conditions. Ring-opening of the molecular ions of 1 followed by a 1, 2-hydrogen shift preceedes the fragmentation consisting mainly in the competitive losses of CH 3 S and ...
