Synthesis and biological evaluation of (+/-)-dinemasone C and analogues.

Dinemasone C was prepared in three steps (8% overall yield) from cis-tetrahydro-4-hydroxy-6-methyl-2-pyrone by aldol reaction with 2,4-hexadienal, epoxidation followed by cyclization, and epimerization of the ring fusion. Dinemasone C, epi-dinemasone C, anhydrodinemasone BC, and nor-dinemasone B are active against bacteria, including Legionella pneumophila Corby, algae, and fungi.