A rhodium-catalyzed cyclization of 1-(trifluoromethyl)-4-alkyn-1-ones with arylboronic acids is described to yield a novel class of small rings: (trifluoromethyl)cyclobutanols bearing an exocyclic double bond. The use of a rhodium/chiral diene complex allowed the reaction to proceed under mild conditions, often with high enantioselectivity. An X-ray crystal structure was obtained confirming the formation of the four-membered ring products.

A rhodium-catalyzed conjugate alkynylation/aldol cyclization cascade was developed. Densely functionalized cyclic α-propargyl-β-hydroxyketones were synthesized with simultaneous formation of a C(sp)-C(sp) bond, a C(sp)-C(sp) bond, as well as three new contiguous stereocenters. The transformation was achieved with excellent enantio- and diastereoselectivities using BINAP as the ligand. The synthetic utility of the newly installed alkynyl moiety was exhibited by subjecting the products to an array of derivatizations.

Herein we describe a rhodium-catalyzed enantioselective isomerization of meso-oxabicyclic alkenes to 1,2-naphthalene oxides. These potentially useful building blocks can be accessed in moderate to excellent yields with impressive enantioselectivities. Additionally, experimental findings supported by preliminary computations suggest that ring-opening reactions of bridgehead disubstituted oxabicyclic alkenes proceed through the intermediacy of these epoxides and may point to a kinetically and thermodynamically favored reductive elimination as the origin for the observed enantioselectivities.

The diterpenoid alkaloids serve as a rich source of synthetic targets for organic chemists, due to the intriguing structure of the overlapping ring systems, along with biological activities commonly associated with compounds of this group. Fifteen total syntheses and numerous synthetic studies towards construction of ring fragments have been reported since 2010. This review article gives a brief overview of diterpenoid alkaloids and summarizes the recent synthetic efforts.1 Introduction1.1 Structural Classification and Biosynthetic Origin1.2 Structure Elucidation of the Aconitum Alkaloids2 Total Syntheses2.1 C18-Diterpenoid Alkaloids2.2 C19-Diterpenoid Alkaloids2.3 C20-Diterpenoid Alkaloids3 Strategies To Synthesize Ring Systems3.1 Radical-Based Cyclizations3.2 Ruthenium-Mediated Enyne Cycloisomerization3.3 Reductive Coupling3.4 Diels–Alder Reactions3.5 Oxidative Dearomatization/Diels–Alder Sequence3.6 Transannular Aziridation3.7 Intramolecular [5+2] Cycloaddition3.8 Miscellaneous4 Conclusion

Nematode parasites of humans, livestock and crops dramatically impact human health and welfare. Alarmingly, parasitic nematodes of animals have rapidly evolved resistance to anthelmintic drugs, and traditional nematicides that protect crops are facing increasing restrictions because of poor phylogenetic selectivity. Here, we exploit multiple motor outputs of the model nematode C. elegans towards nematicide discovery. This work yielded multiple compounds that selectively kill and/or immobilize diverse nematode parasites. We focus on one compound that induces violent convulsions and paralysis that we call nementin. We find that nementin stimulates neuronal dense core vesicle release, which in turn enhances cholinergic signaling. Consequently, nementin synergistically enhances the potency of widely-used non-selective acetylcholinesterase (AChE) inhibitors, but in a nematode-selective manner. Nementin therefore has the potential to reduce the environmental impact of toxic AChE inhibitors that are used to control nematode infections and infestations.