An iterative synthesis of nitrogen-containing polyketides has been developed. Structurally diverse polyketides with nitrogen functional groups were obtained by the uniform protocol.

A decarboxylative condensation of malonic acid half thioesters (MAHTs) with aldehydes catalyzed by benzylammonium trifluoroacetate has been developed for the synthesis of (E)‐α,β‐unsaturated thioesters. The reaction of aromatic aldehydes and sterically non‐demanding aliphatic aldehydes proceeded smoothly at room temperature in DMF in a stereo‐ and regioselective manner. Besides the unsubstituted malonate, 2‐fluoro‐ and 2‐methylmalonates could be employed as a nucleophile. Use of the present catalyst could avoid nonproductive protiodecarboxylation of MAHTs.