A complete experimental and theoretical study of the thermally controlled metal-free decarboxylative hetero-Diels–Alder (HDA) reaction of 5-alkoxyoxazoles with acrylic acid is reported. This strategy offers a new entry to valuable 2, 6-difunctionalized 3- hydroxypyridines from readily available 2-and 4-disubstituted 5-alkoxyoxazoles. The reaction conditions proved compatible with, among others, ketone, amide, ester, ether, ...