An efficient method for generation of α-oxoketenes: Cycloreversion of enolized Meldrum's acid derivatives

Article abstract of DOI:10.1016/S0040-4039(97)01566-9

A series of 6-methoxy- or siloxy-4H-1,3-dioxin-4-ones was synthesized from Meldrum's acids. These dioxinones underwent 4+2 cycloreversion to methoxy- or siloxycartbonylketenes and ketones quantitatively at 20-50°C. The ketenes were characterized by IR spectroscopy as well as by trapping with t-butanol. The ready cycloreversion of these enolized Meldrum's acid derivatives strongly indicates that the anomalously high susceptibility of Meldrum's acids to nucleophilic reagents is due to the participation of carboxyketenes generated through the cycloreversion of tautomeric 6-hydroxydioxinones.