Diastereoisomeric enrichment of 1,4-enediols and H 2 -splitting inhibition on Pd-supported catalysts.

Pd-supported catalysts are fundamental tools in organic reactions involving H 2 splitting. Here we show that 1,4-enediols enriched in one diastereoisomer are produced from the classical Pd-catalyzed semi-hydrogenation reaction with H 2 , starting from the corresponding, widely available 1,4-diacetylenic diols. The semi-hydrogenation reaction proceeds concomitantly with the desymmetrization of the meso /racemic form of the enediol. We also show that these products, if added in advance to H 2 , completely inactivate the Pd catalyst (only when added before H 2 ). These results provide a simple way not only to produce 1,4-enediols enriched in one diastereoisomer by a classical catalytic method but also to stop H 2 dissociation on Pd nanoparticles.