| Affiliation: | 1. Organic Chemistry Laboratory, University Bayreuth, Universitätsstrasse 30, 95440 Bayreuth, Germany;2. Department of Compound Profiling and Screening, Helmholtz Center for Infection Research GmbH, Inhoffenstrasse 7, 38124 Braunschweig, Germany Department of Biochemistry and Biotechnology, Technical University of Kenya, P.O. Box 52428 –, 00200 Nairob, Kenya;3. Department of Compound Profiling and Screening, Helmholtz Center for Infection Research GmbH, Inhoffenstrasse 7, 38124 Braunschweig, Germany |
| Abstract: | Two pairs of side-chain epimeric 3-methoxycarbonyl-dihydrofuran-4-ones with structures purported for thiocarboxylics C1/2 and gregatins G1/2, 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. The optimum protecting group for the 10-OH group in the dienyl side-chain, orthogonal to necessary protecting groups on O-10 of the furanone, was found to be t-butyldiphenylsilyl (TBDPS). The specific rotations of our synthetic products deviated markedly from those reported for the natural isolates. In contrast to the isolates, the synthetic products were not active against Escherichia coli and Staphylococcus aureus bacteria. |
