Acylation reaction of γ,β‐unsaturated β‐keto esters and of ethyl hydrogen malonate. Synthesis of 6‐alkenyl‐5‐ethoxycarbonyl‐2,3‐dihydro‐4 H ‐pyran‐4‐ones and 4,5‐dioxo‐2,3,7,8‐tetrahydro‐4 H ,5 H ‐pyrano[4,3‐ b ]pyran derivatives

The syntheses of 6‐alkenyl‐5‐ethoxycarbonyl‐2,3‐dihydro‐4 H ‐pyran‐4‐one derivatives by acylation of γ,β‐unsaturated β‐keto esters or by diacylation of ethyl hydrogen malonate with α,β‐unsaturated acyl chlorides are described. These compounds were converted to 4,5‐dioxo‐2,3,7,8‐tetrahydro‐4 H ,5 H ‐pyrano[4,3‐ b ]pyran derivatives.