A phosphoric acid with a 1,1′-spirobiindane-7,7′-diol (spinol) backbone and two pendant thioxanthone groups was found to promote the photochemical deracemization of 2,3-allenoic acids.
An aerobic double functionalization of 2,3-allenoic acids with terminal alkynes has been achieved affording versatile 4-alkynylfuran-2(5H)-one derivatives, which have been demonstrated as platform molecules for synthesis of useful natural products.
I2/CF3CO2Ag-mediated iodolactonization of allenoic acids has been developed to synthesize various 6- to 9-membered ring vinylic iodolactones in 16–89% yield.
A variety of optically active tertiary propargylic alcohols and tetrasubstituted 2,3-allenoic acids have been synthesized via a Pd((R)-DTBM-SEGphos)Cl2-catalyzed carboxylative kinetic resolution reaction of racemic tertiary propargylic alcohols.
The stereoselectivity of the title reaction is governed by the substitution pattern within the allene substrate and by the choice of Lewis acid catalyst allowing a facile access to bicyclo[2.2.1]heptenes with an exocyclic double bond.