The structure elucidation and total synthesis of β-lipomycin.

Here we describe the synthesis of β-lipomycin, a secondary metabolite isolated from the fermentation broth of Corallococcus coralloides. The synthesis relies on the structural assignment made by a statistical method, the so-called profile hidden Markov model. Using this protocol, not only the configuration of the secondary alcohol, but also of the adjacent methyl branch could be deduced.

The vinylogous Mukaiyama aldol reaction (VMAR) in natural product synthesis.

The vinylogous Mukaiyama aldol reaction (VMAR) allows efficient access to larger segments for complex natural product synthesis, primarily polyketides, through the construction of vicinal hydroxyl and methyl groups as well as di and tri-substituted double bonds in one single operation. In this review, we will highlight stereoselective protocols that have been used in natural product synthesis and cluster them into the four groups that can be obtained from different silyl ketene acetals or enol ethers. At the beginning, an overview on different stereoselective VMARs is presented; disregarding their applications in total syntheses.

Structure elucidation and total synthesis of kulkenon.

The impressive biological profile of secondary metabolites isolated from strains of Sorangium cellulosum prompted us to initiate synthetic studies on kulkenon, also isolated from Sorangium cellulosum. The synthesis features a syn-selective vinylogous Kobayashi aldol reaction, recently developed by us, and a ring-closing intramolecular Heck reaction as the pivotal transformations. Comparison of the NMR spectra of the authentic and synthetic material revealed that the proposed configuration had to be revised.

Synthesis of angiolam A.

The first total synthesis of angiolam A has been accomplished in 18 steps. Key steps include vinylogous Mukaiyama aldol reactions of aldehyde-derived dienol ethers, conjugate reduction of the resulting double bond followed by diastereoselective protonation and the Witzeman protocol for macrolactamization. Comparison of the optical rotation of the synthesized material with the isolation data established that the absolute configuration of angiolam A is opposite from the proposed structure.

The total synthesis of (-)-aurafuron A.

The first total synthesis of (-)-aurafuron A is presented. It features a Suzuki cross-coupling reaction and a high yielding anionic aldol addition as central carbon skeleton building reactions. The synthesis confirms the proposed structure including its configuration and allows for detailed SAR studies.

Syn-selective vinylogous Kobayashi aldol reaction.

The Kobayashi aldol reaction has become a prominent transformation in polyketide syntheses. This methodology takes advantage of the directing effects of the Evans auxiliary and allows the stereoselective incorporation of a four carbon segment with two additional methyl branches establishing an anti-relationship between the two newly formed chiral centers. So far this transformation was restricted to anti-aldol products.