Synthesis and utility of a novel methylene Meldrum's acid precursor

Article abstract of DOI:10.1055/s-1996-4201

The betaine 1-[(6-hydroxy-2,2-dimethyl-4-oxo-4H-1,3-dioxin-5-yl)methyl]pyridinium hydroxide, inner salt (1), a pyridine adduct of methylene Meldrum's acid is a stable source of methylene Meldrum's acid. It is a versatile reagent which enhances the yields of Diels-Alder and Michael reactions when used instead of traditional methods that generate methylene Meldrum's acid in situ. Diels-Alder reactions performed with this reagent provide products in essentially quantitative yields. Michael reactions result in products in excess of 70% yield. This reagent provides a useful synthetic route to γ-carboxyglutamic acid.