Multisubstituted isoquinoline and pyridine N-oxides have been prepared by Rh(III)-catalyzed cyclization of oximes and diazo compounds via aryl and vinylic C-H activation. This intermolecular annulation involving tandem C-H activation, cyclization, and condensation steps proceeds under mild conditions, obviates the need for oxidants, releases N2 and H2O as the byproducts, and displays a broad substituent scope.

Link! Two, three, four! A rapid and flexible synthesis of native (1→n)‐linked C‐disaccharides (n=2, 3, 4; left) is possible. The configuration of the pseudoanomeric carbon was readily established by an epoxidation/ring‐opening sequence. The synthesis of (1→n)‐linked 2‐deoxy‐C‐disaccharides (right) with high diastereoselectivity follows an even shorter route.

The cooperative catalysis by palladium and triphenylborane effects the intramolecular oxycyanation of alkenes through the cleavage of O-CN bonds and the subsequent insertion of double bonds. The use of 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) as a ligand for palladium is essential for allowing the transformation to proceed with high chemo- and regioselectivity. Variously substituted dihydrobenzofurans with both a tetra-substituted carbon and cyano functionality are accessed by the newly developed methodology.

Herein we describe the synthesis of highly substituted chromans and isochromans using carbohydrates as starting materials. Our approach makes use of a Pd-catalyzed domino reaction consisting of oxidative addition, followed by two carbopalladation steps and completed by a cyclization to annelate the benzene moiety. The versatility of this route has been demonstrated by a small library of highly substituted chromans and isochromans.

A flexible and robust method for the assembly of (1-->6)-linked C-glycosidic disaccharides is presented. The key reaction is a Pd-catalyzed coupling of 1-iodo- or 1-triflato-glycals with alkynyl glycosides. Reinstallation of the native hydroxyl group pattern is achieved after selective hydrogenation of the triple bond using Raney-nickel. Epoxidation with DMDO and reductive epoxide opening gives access to either the alpha- or the beta-derivative, depending on the hydride source.

Biologically interesting fused oligocyclic lactams have been prepared via an intramolecular redox-neutral cyclization process. By the proper choice of the substrates with a wide variety of tethered olefins, the less favored C-H bond can be activated and functionalized. This C-H activation proceeds under mild conditions, obviates the need for external oxidants, and displays a broad scope with respect to the substituents.

The development and application of a new generation of non-C2-symmetric ProPhenol ligands is reported herein. Rational design of the ProPhenol ligand paved the way to the first catalytic and asymmetric vinylation of N-Boc imines via hydrozirconation giving rise to valuable allylic amines in excellent yields and enantioselectivities. The utility of this method was demonstrated by developing the shortest reported asymmetric synthesis of the selective serotonine reuptake inhibitor (SSRI) (-)-dapoxetine.

SummaryHerein, we report on our findings of the Sonogashira–Hagihara reaction with 1-iodinated and 2-brominated glycals using several aromatic and aliphatic alkynes. This Pd-catalyzed cross-coupling reaction presents a facile access to alkynyl C-glycosides and sets the stage for a reductive/oxidative refunctionalization of the enyne moiety to regenerate either C-glycosidic structures or pyran derivatives with a substituent in position 2.