Solid-Phase Mannich Condensation of Amines, Aldehydes, and Alkynes:  Investigation of Diverse Aldehyde Inputs

Terminal alkynes, secondary amines, and aldehydes undergo “solid-phase Mannich condensation”. A set of diverse aldehyde inputs was examined. Aliphatic, aralkyl, aryl, and heteroaryl carboxaldehydes give good yields of Mannich adduct of high purity. Benzaldehydes containing electron-donating substituents that decrease the electrophilicity of the carbonyl center, or heteroaryl aldehydes that are similarly deactivated by resonance effects, do not undergo reaction.