Acetic acid asymmetric hydroformylation

The asymmetric hydroformylation of functionalized aliphatic alkenes is generally more difficult than the hydroformylation of vinyl arenes. The rhodium-catalyzed hydroformylation of vinyl acetate (36) yields 2- and 3-acetoxypropanals, 37 and 38, with high chemoselectivity. Ethyl acetate and acetic acid can also be found as by-products. One of the potential applications of vinyl acetate hydroformylation is the production of enantiopure propane 1,2-diol (Scheme 6). 

Scheme 4.66 Asymmetric hydroformylation of vinyl acetates and final preparation of lactic acid and threonine.

Bestmann s ylide 0=C=C=PPh3 as a Cj buUding block (Scheme S.ldO). ) The required substrate was derived by the rhodium-catalyzed addition of acetic acid to a terminal alkyne. For the asymmetric rhodium-catalyzed hydroformylation at 10.3 bar, Landis s (S,S,S)-BDP was used as ligand. After hydroformylation and ring closure, the protecting 0-acetyl group was removed by the effect of an enzyme to finally produce (+)-patulolide C in an overall yield of 49%. 

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