Proline promoted synthesis of ring-fused homodimers: self-condensation of alpha,beta-unsaturated aldehydes.

1,2,4-Trisubstituted cyclohexadienals can be prepared synthetically by self-condensation of beta-methyl substituted alpha, beta-unsaturated aldehydes. While molecules with this structural scaffold have been observed in nature, the biological roles of these compounds have yet to be thoroughly investigated. Here we investigate the use of L-proline and its derivatives to effect synthesis of these ring-fused homodimers. The scope of this reaction is investigated with different substrates and proline derivatives. Mechanistic hypotheses are put forth supported by NMR and mass spectrometry studies. The method will enable diversification of this scaffold in sufficient quantities for biological investigations.