Enantiomerically pure acylketene acetals were employed to generate a homochiral p-keto ketal through a highly diastereoselective lithium enolate quench. The fi-keto ketal, which was also prepared through a desymmetrization ketulizution reaction on a meso dione, was employed in the synthesis of the isomers of the insect pheromone sitophilure.
We recently reported that achiral acylketene acetals undergo conjugate hydroboration-reduction and conjugate organolithium addition reactions. With organolithium reagents, the resulting lithium enolate could be quenched with methyl iodide in good yield. ' From these results, we hypothesized that a homochiral acylketene acetal (such as i) would follow the same reaction pathway and undergo a, diastereosdective enolate quench, In addition, diastereoselective reduction of the resultant monoprotected P-dicarbonyl compounds would lead to a new, non-aldol route to chiral, nonracemic P-hydroxy carbonyls.2 Such a protocol would allow for a unified approach to the array of P-hydroxy carbonyl compounds of different oxidation states and substitution pattern, as shown be10w.~ Herein we report our studies in this area. Further,