Formal gas-phase polar [4 + 1+] cycloaddition of ionized methylene to alpha-dicarbonyl compounds: synthesis of 2-unsubstituted 1,3-dioxoles.
Ion/molecule reactions of +CH2OCH2. with alpha-dicarbonyl compounds were performed via pentaquadrupole mass spectrometry. Besides the previously known [3+ + 2] 1,3-cycloaddition reaction that forms cyclic 1,3-dioxonium ions, an unprecedented reaction proceeding formally by [4 + 1+] cycloaddition of ionized methylene (CH2+.) to the alpha-dicarbonyl compounds occurs competitively, leading to the gas-phase synthesis of several ionized 2-unsubstituted 1,3-dioxoles. This novel cycloaddition reaction may therefore be added to the set of methods available for the synthesis of 1,3-dioxoles.
Meurer
Eduardo C
EC
ThoMSon Mass Spectrometry Laboratory, Institute of Chemistry, State University of Campinas, 13084-971 Campinas SP, Brazil.
Cabrini
Liliane G
LG
Gozzo
Fabio C
FC
Eberlin
Marcos N
MN