Syntheses and Antibacterial Evaluation of New Penicillium Metabolites Gregatins G and Thiocarboxylics C.

Two pairs of side-chain epimeric 3-methoxycarbonyl-dihydrofuran-4-ones with structures purported for thiocarboxylics C and gregatins G , isolated from Penicillium sp. Sb62, were synthesised for the first time in five steps and 17-25 % yield. Key steps were a Suzuki cross-coupling, a Yamaguchi esterification, and a base-induced Knoevenagel-type condensation.

Synthesis and Bioactivity of Thiocarboxylic A and Derivatives.

The metabolite thiocarboxylic A () and three close analogues were synthesized in 14 steps. The stereogenic elements were installed via stereoselective Sharpless epoxidation, ()-selective reduction of a dibromide, and a Suzuki cross coupling. Thiocarboxylic A () was obtained in 6% overall yield.

Synthesis and Bioactivity of Ophiofuranones A and B.

Ophiofuranones A and B, metabolites of the fungus , were synthesized in 16 steps and 12%/22% yield. The stereogenic centers were established by Sharpless dihydroxylations and epoxidation, the 1,3-dienes via Wittig or HWE olefinations. The rings were closed through Knoevenagel-type condensation and lactonization.