Organocatalytic Enantioselective [3+2] Cycloaddition of Azomethine Ylides with 2,4-Dienals: Construction of Remote Stereogenic Centers via 1,6-Addition Reaction

A regio- and stereoselective [3+2] cycloaddition of phthalazinium dicyanomethanides with 2,4-dienals was achieved with the use of a commercially available MacMillan's calalyst via LUMO-lowering activation. The reaction proceeds through 1,6-additon to linear 2,4-dienals with remote control over stereochemistry, affording the cycloadducts having three stereogenic centers.