Answers are grounded in this paper and cite their sources.
Various γ-lactones bearing vinylic substituent on β-position were obtained directly by the thermal condensation of trans-2-alkene-1,4-diols with orthocarboxylic esters in the presence of a catalytic amount of hydroquinone or phenol.
No takes yet. Share an insight, caveat, or question.
Kondô et al. (1974) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: