SYNTHESIS AND UTILITY OF A NOVEL METHYLENE MELDRUMS ACID PRECURSOR

The betaine imethyl-4-oxo-4H-1,3-dioxin-5-yl)methyl]pyridinium hydroxi de, 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 us ed instead of traditional methods that generate methylene Meldrum's ac id 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 syn thetic route to gamma-carboxyglutamic acid.