Additions of 1,1-Diethoxyethene to 1,2-Diketones

Article abstract of DOI:10.1021/jo00216a002

The ketene acetal 2 undergoes thermally noncatalyzed additions to various 1,2-diketones under formation of <1:1>- and <1:2>-adducts.Only with biacetyl 1a could an oxetane, 3, be isolated whereas mainly substituted 6-oxo-2,4-hexadienoic acid ethyl esters 6 and 7 are formed with aromatic 1,2-diketones.The regioselectivities and the product ratios are discussed in terms of a mechanism via zwitterionic intermediates.