Synthesis, Stability, and Diels‐Alder Reactions of Methyl 2‐Oxobut‐3‐enoate

Methyl vinyl glycolate (MVG, methyl 2‐hydroxybut‐3‐enoate) is a new biobased platform chemical, which is available by degradation of carbohydrates. In the present work, the oxidation of MVG to methyl 2‐oxobut‐3‐enoate has been investigated and a procedure developed with the Dess‐Martin periodinane. Methyl 2‐oxobut‐3‐enoate has not been characterized before and is stable for days at −18 °C, but slowly dimerizes by an unusual hetero‐Diels‐Alder reaction at room temperature. Therefore, the reactivity of methyl 2‐oxobut‐3‐enoate in the normal Diels‐Alder reaction with 1,3‐dienes has been investigated and a one‐pot procedure developed where MVG is first oxidized with the Dess‐Martin periodinane followed by the addition of the 1,3‐diene. A number of different 1,3‐dienes can take part in the cycloaddition to afford the functionalized cyclohexene products in moderate‐to‐good yields. Bio‐based methyl vinyl glycolate (MVG) has been oxidized to methyl 2‐oxobut‐3‐enoate with the Dess‐Martin periodinane. Densely functionalized methyl 2‐oxobut‐3‐enoate is stable at low temperatures but slowly dimerizes by a hetero‐Diels‐Alder reaction at room temperature. Accordingly, methyl 2‐oxobut‐3‐enoate has been developed as a new dienophile in the classical Diels‐Alder reaction with 1,3‐dienes