Evidence for the occurrence of an oxygen to oxygen acyl shift in 7‐acetoxybicyclo|3,2,0|heptan‐2‐ones upon chemical ionization mass spectrometry

Abstract

SUMMARYAn oxygen to oxygen acyl migration has been observed in 7-acetoxybicyclol3, 2,Olheptan-2-ones upon isobutane chemical ionization mass spectrometry. The mechanism of this rearrangement is discussed and is investigated by means of deuterium labelling techniques.Isobutane chemical ionization (CI) mass spectrometry has proven to provide valuable regio-and stereochemical information on ( 2 + 2) photocycloaddition products between cyclopent-2-enones and various alkenes2' 3. a study on the reaction products between cyclopent-2-enone and ethyl-6-acetoxyacrylate, which are of synthetic interest for the preparation of prostanoid synthons', a CI induced acyl shift has been observed. migrations have not been reported so far to occur in a CI plasma, but have been described in strong acid medium for acylated peptides . Since resemblancies have been noted between reactions in strong acid medium and in a CI plasma, we thought it was of interest to study this CI induced acyl migration into detail. hh ht +