An efficient method for the synthesis of 5-vinyl-2-isoxazolines by Pd-catalyzed intramolecular O-allylation of ketoximes has been developed. The reaction involves Pd(0)-catalyzed π-allyl formation via leaving group ionization or Pd­(II)-catalyzed allylic C–H activation followed by intramolecular nucleophilic oxime oxygen attack. This methodology has been elaborated to various value-added products by epoxidation, Wacker oxidation, cross-metathesis, hydroboration–oxidation, dihydroxylation, and catalytic hydrogenation.

The naturally occurring (4R,5R)-4-hydroxy-γ-decalactone from the Japanese orange fly and the antipode of (4S,5R)-4-hydroxy-γ-dodecalactone from the harvestmen arachnid and their stereoisomers are synthesized from the chiral pool material d-glucono-δ-lactone in a few steps. The one-pot conversion of the latter to γ-vinyl-β-hydroxy-γ-lactone, cross-metathesis with requisite olefin, and hydrogenation enabled the synthesis of syn-lactones in just a two-pot operation. An additional efficient Pd-catalyzed allylic isomerization of γ-vinyl-β-hydroxy-γ-lactone led to the anti-lactones in high yields.

An efficient method for the synthesis of (E)-(3-alkoxybut-1-enyl)­benzenes by Pd-catalyzed regioselective intermolecular hydroalkoxylation of 1-arylbutadienes has been developed. This method can be executed in a simple operation with no dry reaction conditions required and having tolerance to a wide range of substrates. Chloromethyl methyl ether (MOMCl) as an additive was found to be essential for the success of the reaction.

In this review, we have described various syntheses of disparlure (a sex pheromone emitted by female gypsy moth), its stereoisomers and analogues over the last three decades (1989−2020). The vast...