Participation π dans la solvolyse des diazocétones primaires. Communication préliminaire

In the acid catalyzed hydrolysis of 5,6‐unsaturated diazoketones of suitable geometry (Ib, IIb, IIIb, IVb, VIb), participation of the double bond in the reaction of the diazonium ion is proved (a) by the formation of cyclisation products, and (b) in some cases by the acceleration of the rate determining S N 2 substitution process. In the case of VIb the substitution step is so much accelerated that the pre‐equilibrium protonation step becomes rate determining (evidence: inversion of the kinetic solvent isotope effect).