New Developments in Putting Waste to Work

Significance

Lu and Toy report a tandem Wittig reductive aldol cascade, which combines five reactions in a one-pot operation. In particular, the authors achieved the formation of the stabilized Wittig reagent B from α-halo ketones 1, followed by the Wittig reaction with aldehyde 2, reduction of the resulting enone C with HSiCl₃ to silyl enol ether D and the final aldol reaction with aldehydes 2 or 3 to give products 4 or 5, respectively. Yields of up to 85% demonstrate excellent efficiency over five consecutive synthetic steps. Importantly, the silane reduction (C → D) is catalyzed by triphenyl phosphine oxide, a byproduct of the initial ­Wittig reaction.