Correction: A synthetic study toward the core structure of (−)-apicularen A

Correction for ‘A synthetic study toward the core structure of (−)-apicularen A’ by Tapas R. Pradhan et al., Org. Biomol. Chem., 2018, 16, 8810–8818.

A synthetic study toward the core structure of (−)-apicularen A

A concise synthetic strategy towards the core structure of (−)-apicularen A has been described in an 11-step synthetic sequence from a known intermediate.

C-O Ring Construction: (-)-Sclerophytin A (Morken), (+)-Dictyosphaeric Acid (Taylor), Goniothalesdiol A (Xie/She), (-)-7-Deoxyloganin (Lupton), (-)-Apicularen A (Uenishi), L-783, 277(Banwell) 100

In the course of a synthesis of (-)-sclerophytin A 3, James P. Morken of Boston College showed (J. Am. Chem. Soc. 2010, 132, 16380) that Oshima-Utimoto conditions transformed 1 into 2 with high stereo-and regiocontrol. En route to (+)-dictyosphaeric acid 6, Richard J. K. Taylor of the University of York found (Angew. Chem. Int. Ed. 2010, 49, 5574) that the intramolecular Michael cyclization of 4 proceeded smooothly to give 5. Xingang Xie and Xuegong She of Lanzhou University devised (Synlett 2010, 2283) the In-mediated cyclization of 7 with benzaldehyde, to effect an elegant synthesis of goniothalesdiol A 9. The carbene-mediated cyclization of 10 to 11 developed (Org. Lett. 2010, 12, 4836) by David W. Lupton of Monash University set the stage for the synthesis of (-)-7-deoxyloganin 12. Jun’ichi Uenishi of Kyoto Pharmaceutical University showed (Org. Lett. 2010, 12, 4160) that the Pd-mediated cyclization of 13 proceeded with high diastereocontrol. Intramolecular esterification than led to (-)-apicularen A 15. Martin G. Banwell of the Australian National University established (Heterocycles 2010, 82, 313) that LiHMDS was effective for the cyclization of the alkynyl Weinreb amide 16 to 17. Reduction and deprotection completed the synthesis of the resorcylic lactone L-783, 277 18.

Synthesis of myxobacteria metabolites

Myxobacteria are an excellent source of novel secondary metabolites with a range of biological activities. This review details the synthesis of several examples of these natural products. The total synthesis of all the members of the crocacin family is presented where the stereochemistry of the stereotetrad was set via a tin-mediated syn-aldol reaction followed by selective anti-reduction. The other key step in the route to crocacins A, B, and D was the introduction of the enamide functionality by acylation of an enecarbamate. A formal synthesis of apicularen A is also discussed, which involved a base-induced macrolactonization reaction and a transannular oxy-Michael cyclization to secure the tetrahydropyran ring. Finally, the total synthesis of deshydroxyajudazol B is summarized. This route details a modified approach to the 2,4-disubstituted oxazole, and a Diels–Alder reaction followed by aromatization was utilized to form the isochromanone moiety. A highly efficient Sonogashira coupling followed by partial reduction then gave deshydroxyajudazol B.