Abstract The hetero-Diels-Alder reaction between aldehydes, 2, and bis-1, 1-dimethoxy-3- trimethyl-1-siloxy-1, 3-butadiene, 1, produces 2-methoxy-5, 6-dihydro-γ-pyrones, 4, which are subsequently hydrolyzed to afford substituted 3-oxo-δ-lactones, 5, in high yields, providing a new and efficient approach to these synthetically useful intermediates.
