Novel Synthesis of Five- and Six-Membered Spiro γ-Lactones in Rigid Bicyclic Systems
The reaction of bis(bromomagnesio)alkanes with bridged tricyclic endo- and exo-dicarboxylic anhydrides and their dihydro derivatives provides a general and versatile route to corresponding tricyclic spiro γ-butanolides.Futher extension of this methodology to the dianhydride of bicyclooctene showed appreciable regioselectivity.The subsequent transformation of spiro γ-lactones into 4-spiro-2-butenolides by retro-Diels-Alder reaction has provided a simple and convenient synthesis of these molecules.Proton and 13C NMR spectra are reported for most of the compounds.
Cannone, Persephone,Belanger, Denis,Lemay, Gilles
p. 3953 - 3959
(2007/10/02)
A FACILE AND GENERAL ROUTE TO 4-SUBSTITUTED-2 BUTENOLIDES
Grignar reagents react with 7-oxabicyclohept-5-ene-2,3-dicarboxylic anhydride and produce in high yields the corresponding substituted bicyclo-γ-butanolides.These lactones produce the title compounds by retro Diels-Alder reaction during distillation.