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The daphnezomine A‐type subfamily of Daphniphyllum alkaloids structurally features a unique aza‐adamantane core skeleton and anticipates efficient strategies for completing their syntheses to thoroughly investigate their biological activities. Herein, divergent total syntheses of (−)‐daphnezomines A and B and (+)‐dapholdhamine B have been accomplished in 16–20 steps from a known epoxide via rapid construction of a common core intermediate. The present work features a Ti‐mediated radical cyclization to establish the azabicyclo[3.3.1]nonane ring system, an intramolecular Heck reaction to install the bridgehead all‐carbon quaternary stereocenter, a tandem deprotection/reduction/keto amine‐carbinolamine tautomerization to furnish the aza‐adamantane backbone, and an NIS‐promoted 6‐endo‐trig aminocyclization to assemble the (+)‐dapholdhamine B backbone. [ABSTRACT FROM AUTHOR]

Switchable approaches to accomplish the C3-aminomethylation and C3-arylmethylation of imidazo[1,2-a]pyridines with N-methylanilines using distinct electrochemical conditions have been developed. These two transformations exhibited notable regio- and chemoselectivities under air and metal/oxidant-free conditions. Remarkably, the environmentally benign electrochemical methods could be extended to the late-stage derivatization of natural products and drugs using N-methyl amines as a 1C source. [ABSTRACT FROM AUTHOR]

Abstract: Rhodium‐iminocarbenes that are derived from N‐sulfonyl‐1,2,3‐triazoles have become an important class of reactive species and useful intermediates in organic synthesis. Over the last several years, many practical and versatile approaches involving rhodium‐iminocarbene intermediates to synthetically challenging molecules (scaffolds) have been developed. This Minireview mainly summarizes the recent advance of rhodium‐iminocarbene involved reactions in the synthesis of natural products and their related scaffolds by the end of 2017. Several applications in important pharmaceuticals are documented as well. [ABSTRACT FROM AUTHOR]

Abstract: A unified protocol for the construction of 6H‐benzofuro[2,3‐b]indoles and 5,6‐dihydroindolo[2,3‐b]indoles via UV light‐mediated diradical cyclization was developed and preliminary efforts were also made to functionalize at C10b position of 6H‐benzofuro[2,3‐b]indoles. This mild and facile strategy may have great potential in the syntheses of natural products and functional materials. [ABSTRACT FROM AUTHOR]

Abstract: (−)‐Daphnilongeranin B and (−)‐daphenylline are two hexacyclic Daphniphyllum alkaloids, each containing a complex cagelike backbone. Described herein are the first asymmetric total synthesis of (−)‐daphnilongeranin B and a bioinspired synthesis of (−)‐daphenylline with an unusual E ring embedded in a cagelike framework. The key features include an intermolecular [3+2] cycloaddition, a late‐stage aldol cyclization to install the F ring of daphnilongeranin B, and a bioinspired cationic rearrangement leading to the tetrasubstituted benzene ring of daphenylline. [ABSTRACT FROM AUTHOR]

Described herein is the first asymmetric total synthesis of (+)-harringtonolide, a natural diterpenoid with an unusual tropone imbedded in a cagelike framework. The key transformations include an intramolecular Diels-Alder reaction and a rhodium-complex-catalyzed intramolecular [3+2] cycloaddition to install the tetracyclic core as well as a highly efficient tropone formation. [ABSTRACT FROM AUTHOR]

An efficient synthetic route toward the highly congested [5-6-7] tricyclic core of calyciphylline A-type alkaloids has been developed. This approach features a highly efficient intramolecular Diels-Alder cycloaddition to establish the aza-five-membered C ring as well as the C1 all-carbon quaternary center, and a subsequent cyclopropanation together with a ring-expansion reaction of the resulted adduct to construct the seven-membered D ring. [ABSTRACT FROM AUTHOR]

We report a concise synthesis of tanikolide 1, which was obtained from ethyl 2-oxocyclopentanecarboxylate in four steps: alkylation, Baeyer–Villiger reaction, saponification, and reduction/lactonization, in 70% overall yield. Our strategy should be suitable for the preparation of 1 in multigram or larger quantities. The net result of the last two steps (i.e. saponification and reduction/lactonization) is an efficient reduction of the ethoxycarbonyl of 3 while keeping the lactone carbonyl intact. [Copyright &y& Elsevier]