The combined use of aluminumtris(2,6-diphenylphenoxide) (ATPH) and lithium 2,2,6,6-tetramethylpiperidide (LTMP) has proven to be effective for the mixed crossed aldolcondensation between conjugated esters and various aldehydes. An example is shown in Equation (1).
The iterativepolyketidesynthases from the biosynthetic pathways of three enediyne natural products were examined. The results established the all-trans conjugated pentadecaheptanene as the only major product shared by the PKSs. The experiments further revealed some intrinsic differences among the PKSs by demonstrating the formation of different by-products.