GAS-PHASE REACTIONS OF 1,2 5,6-DI-O-ISOPROPYLIDENE-ALPHA-D-GLUCO-FURANOSE AND ALLOFURANOSE WITH ELECTROPHILES DERIVED FROM ACETONE/

In a quadrupole mass spectrometer, under chemical ionization condition s with acetone as the reagent gas, 1,2:5,6-di-O-isopropylidene-alpha-D -glucofuranose and 1,2:5,6-di-O-isopropylidene-alpha-D-allofuranose fo rm M+1, M+43, and M+59 ions in the gas phase. In addition, the allo is omer produces M+41 ions. These ions and the corresponding ions derived from isotopomers in which the isopropylidene groups were differentiat ed by deuterium substitution were separately subjected to collisionall y activated dissociation conditions. The different reactivities of the se ions were attributed to the ability of the allo structure to hydrog en bond internally and the different sizes of the electrophilic groups which formed adducts with the neutral protected sugar molecules.