Concise syntheses of the Cephalotaxus norditerpenoids cephanolides A–D (8–14 steps from commercial material) using a common late-stage synthetic intermediate are described. The success of our approach rested on an early decision to apply chemical network analysis to identify the strategic bonds that needed to be forged, as well as the efficient construction of the carbon framework through iterative Csp2–Csp3 cross-coupling, followed by an intramolecular inverse-demand Diels–Alder cycloaddition. Strategic late-stage oxidations facilitated access to all congeners of the benzenoid cephanolides isolated to date.

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Total synthesis of bottromycin A can be accomplished through a diastereoselective Mannich reaction of a chiral sulfinamide, mercury-mediated intermolecular amidination, and cyclization of a constrained tetracyclic peptide. Exploitation of this process allowed the synthesis of several novel bottromycin analogs. The antimicrobial activity of these analogs was evaluated in vitro against Gram-positive bacteria, such as methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE). Structure-activity relationships were explored taking into consideration the unique three-dimensional structure of the compounds. Notably, one of the new analogs devoid of a methyl ester, which is known to lower the in vivo efficacy of bottromycin, exhibited antibacterial bioactivity comparable to that of vancomycin.

<p>Natural product total synthesis inspires strategy development in chemical synthesis. In the 1960s, Corey and coworkers demonstrated a visionary preparation of the terpenoid longifolene, using “strategic bond analysis” to craft a synthesis route. This approach proposes that efficient synthesis routes to bridged, polycyclic, structures should be formulated to introduce the bulk of the target’s topological complexity at a late stage. In subsequent decades, similar strategies have proved general for the syntheses of a wide variety of bridged, polycyclic molecules. Here, we demonstrate that an orthogonal strategy, which utilizes a topologically complex bicyclo[2.2.1] starting material accessed through a scaffold rearrangement of (<i>S</i>)-carvone, leads to a remarkably short synthesis of the longifolene-related terpenoid longiborneol. We also employ a variety of late-stage C–H functionalization tactics in divergent syntheses of many longiborneol congeners. Our strategy should prove effective for the preparation of other topologically complex natural products that contain the bicyclo[2.2.1] framework.</p>

This article describes the first total synthesis of luminamicin using a strategy combining chemical degradation with synthesis. Chemical degradation studies provided a sense of the inherent reactivity of the natural product, and deconstruction of the molecule gave rise to a key intermediate, which became the target for chemical synthesis. The core structure of the southern part of luminamicin was constructed by a 1,6-oxa-Michael reaction to form an oxa-bridged ring, followed by coupling with a functionalized organolithium species. Modified Shiina macrolactonization conditions forged the strained 10-membered lactone containing a tri-substituted olefin. Diastereoselective α-oxidation of the 10-membered lactone completed the center part to provide the key intermediate. Inspired by the degradation study, an unprecedented enol ether/maleic anhydride moiety was constructed with a one-pot chlorosulfide coupling and thiol β-elimination sequence. Finally, macrolactonization to the 14-membered ring in the presence of the highly electrophilic maleic anhydride moiety was accomplished using modified Mukaiyama reagents to complete the synthesis of luminamicin.