57258-53-4Relevant academic research and scientific papers
Synthesis of 4-Ylidenebutenolides. A Practical Route to 2-En-4-ynoic Acid Intermediates based on Conjugate Addition of Alkynyl-lithium Reagents
Clemo, Nicholas G.,Pattenden, Gerald
, p. 2133 - 2136 (2007/10/02)
Conjugate addition of alkynyl-lithium reagents to diethyl ethoxymethylenemalonate, followed by simultaneous saponification and 1,2-elimination of ethanol from the intermediate adducts, viz (18), in the presence of ethanolic potassium hydroxide, provides a useful synthesis of substituted propargylidenemalonic acids (19).Cyclisation of the propargylidenemalonic acids, using known procedures then leads to the corresponding 4-ylidenebutenolides, e.g. (20) and (21)
Cyclisation of Acetylenecarboxylic Acid. Synthesis of γ-Methylenebutyrolactones
Yamamato, Makoto
, p. 582 - 587 (2007/10/02)
Various γ-exo-methylenebutyrolactones have been synthesized in excellent yield by the cyclisation of acetylenecarboxylic acids in the presence of a catalytic amount of mercury(II) oxide.Cyclisation of terminal acetylene compounds proceeded regioselectively to give γ-exo-methylenebutyrolactones as the sole product.Disubstituted acetylenes also gave the (Z)-configurational enol lactone, but small amounts of an (E)-isomer of a γ-exo-enol lactone and a δ-lactone (α-pyrone) were also formed.Spectral properties and stereochemistry of the exo-enol lactones are also discussed.
