77670-52-1Relevant articles and documents
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.