Last month's blog was about indole and hexanol condensation using the Shvo catalyst and this month Takahashi et al. present a novel way to synthesize n-alkanols (such as hexanol) using the same Shvo catalyst (DOI). The new method describes catalysis of the reaction of a terminal alkene with syngas which is a mixture of CO and hydrogen. The industrial production of n-alcohols relies on an alkene hydroformylation step and a hydrogenation step and rolling them into one should be advantageous. Issues to tackle in academic research thus far are branching and alkane formation. The new Takahashi method (according to Takahashi of course) should provide a breakthrough.
The formylation part is taken care of by (Acetylacetonato)dicarbonylrhodium / xantphos and Svho (with or without phosphine assistance) tackles the hydrogenation. And how does Svho reduce the polar C=O bond while ignoring the apolar reactant C=C bond?: Takahashi reminds the reader that Shvo generates a proton and a hydride ion which simultaneously act with the C=O bond with a polar transition state. Polar aprotic solvent N,N-dimethylacetamide works best.