Pseudocine Substitution of 4-(Mesyloxy)-2-cyclopentenones: An Efficient Route to 2,4-Disubstituted 2-Cyclopentenones

Article abstract of DOI:10.1021/jo00061a010

Readily available mesylates 1a-d were found to undergo a novel substitution reaction.In the presence of a variety of nucleophiles, 1a-d underwent a net substitution in which the nucleophile was introduced vicinally (C-3) to the departing mesylate (C-4) and the double bond migrated to C-4/C-5.Lithium bromide, thiophenol, benzylamine, sodium azide, and the potassium salt of dimethyl malonate all led to substitution products in good yield.The reaction is thought to proceed by way of initial conjugate addition of the nucleophile, followed by enolate equilibration and β-elimination of mesylate.