Derivate der Oxalyldimalonsäure

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Abstract
Derivatives of Oxalyldimalonic AcidStarting with furanone 3 and mesoxalic acid esters, the compounds 8 as monolactones of the title compound have been synthesized. A versatile intermediate is the dioxinone 15, the masked acylketene 16. Regioselective partial saponification of 8a led to the diester 8e which was converted into the dilactone 2. The enamine 8d isomerizes by two pathways. By alkanolate catalysis the γ‐alkylidenetetramic acid 24 was obtained and used to prepare the lactam‐lactone 25 and the dilactam 27. Thermal isomerization of 8d gave the cyclic tetracarbonylmethane derivative 19. Ring opening reactions of 19 did not furnish derivatives of the title compound but the isomeric acids 20–23. Some open‐chain derivatives of oxalylbismalonic acid (12, 26) were obtained from 8c/8d by lactone cleavage.