Biomimetic Synthesis of Meroterpenoids by Dearomatization-Driven Polycyclization.

A biomimetic route to farnesyl pyrophosphate and dimethyl orsellinic acid (DMOA)-derived meroterpenoid scaffolds has yet to be reported despite great interest from the chemistry and biomedical research communities. A concise synthetic route with the potential to access DMOA-derived meroterpenoids is highly desirable to create a library of related compounds. Herein, we report novel dearomatization methodology followed by polyene cyclization to access DMOA-derived meroterpenoid frameworks in six steps from commercially available starting materials. Furthermore, several farnesyl alkene substrates were used to generate structurally novel, DMOA-derived meroterpenoid derivatives. DFT calculations combined with experimentation provided a rationale for the observed thermodynamic distribution of polycyclization products.

Asymmetric Synthesis of Gonytolide A: Strategic Use of an Aryl Halide Blocking Group for Oxidative Coupling.

The first synthesis of the chromanone lactone dimer gonytolide A has been achieved employing vanadium(V)-mediated oxidative coupling of the monomer gonytolide C. An o-bromine blocking group strategy was employed to favor para- para coupling and to enable kinetic resolution of (±)-gonytolide C. Asymmetric conjugate reduction enabled practical kinetic resolution of a chiral, racemic precursor and the asymmetric synthesis of (+)-gonytolide A and its atropisomer.

Room temperature rapid functionalization of E-H bonds (E = O, N, S) via the metal-ligand cooperation mechanism.

An arylpalladium PNF-type pincer complex reacts with water and anilines under very mild conditions, providing access to new PNO- and PNN-pincer complexes with concomitant hydrogen transfer to the ligand core. Such a metal-ligand cooperation mode allows for the irreversible double activation of even highly sterically hindered aniline molecules. With thiols, the activation mode depends on the nature of the substituent at the sulfur atom, with thiophenols giving products of C-S elimination.

Evidence for metal-ligand cooperation in a Pd-PNF pincer-catalyzed cross-coupling.

The first Pd-pincer complex bearing a halogen (fluorine) arm has been prepared via the base-assisted dearomatization of a phosphine-quinoline (P~N) ligand. This dearomatization is reversible and has been used to facilitate catalytic Sonogashira-type cross-coupling that, contrary to the typical mechanistic approach, is based on a metal-ligand cooperation mode.