C-H Activation Enables a Concise Total Synthesis of Quinine and Analogues with Enhanced Antimalarial Activity.

We report a novel approach to the classical natural product quinine that is based on two stereoselective key steps, namely a C-H activation and an aldol reaction, to unite the two heterocyclic moieties of the target molecule. This straightforward and flexible strategy enables a concise synthesis of natural (-)-quinine, the first synthesis of unnatural (+)-quinine, and also provides access to unprecedented C3-aryl analogues, which were prepared in only six steps. We additionally demonstrate that these structural analogues exhibit improved antimalarial activity compared with (-)-quinine both in vitro and in mice infected with Plasmodium berghei.

Chemoselective intermolecular α-arylation of amides.

A new approach for the fully chemoselective α-arylation of amides is presented. By means of electrophilic amide activation, aryl groups can be regioselectively introduced α- to amides, even in the presence of esters and alkyl ketones. Mechanistic studies reveal key reaction intermediates and emphasize a remarkably subtle base effect in this transformation.

Asymmetric total synthesis of a putative sex pheromone component from the parasitoid wasp Trichogramma turkestanica.

Virgin females of the parasitoid wasp Trichogramma turkestanica produce minute amounts of a sex pheromone, the identity of which has not been fully established. The enantioselective synthesis of a putative component of this pheromone, (6S,8S,10S)-4,6,8,10-tetramethyltrideca-2E,4E-dien-1-ol (2), is reported as a contribution to this identification. Catalytic asymmetric conjugate addition of methylmagnesium bromide and stereoselective Horner-Wadsworth-Emmons olefinations are used as the key steps, and 2 was obtained in 16 steps with an overall yield of 4.4%.

Electrophilic rearrangements of chiral amides: a traceless asymmetric α-allylation.

A one-pot protocol for the asymmetric α-allylation reaction is reported relying on a key efficient asymmetric Claisen rearrangement, triggered by electrophilic activation of chiral pseudoephedrine amides. Subsequent reduction or hydrolysis of the resulting iminium ions provides highly enantioenriched α-allylic aldehydes or carboxylic acids in a traceless manner. Compared to traditional alternatives which make use of strongly basic conditions, the work presented herein displays unprecedented functional group tolerance.

Total synthesis of sulfolipid-1.

Sulfolipid-1, a tetra-acylated sulfotrehalose from Mycobacterium tuberculosis, was isolated over 40 years ago. Being a main component of the mycomembrane of M. tuberculosis, its biosynthesis and function have been studied in depth, but the chemical synthesis of sulfolipid-1 has not been reported. The synthesis presented here is based on iterative catalytic asymmetric conjugate additions of methylmagnesium bromide for the preparation of the phthioceranic and hydroxyphthioceranic acid side chains, a double regioselective reductive ring-opening and a fivefold deprotection in the final step.

Catalytic enantioselective syn hydration of enones in water using a DNA-based catalyst.

The enantioselective addition of water to olefins in an aqueous environment is a common transformation in biological systems, but was beyond the ability of synthetic chemists. Here, we present the first examples of a non-enzymatic catalytic enantioselective hydration of enones, for which we used a catalyst that comprises a copper complex, based on an achiral ligand, non-covalently bound to (deoxy)ribonucleic acid, which is the only source of chirality present under the reaction conditions. The chiral ß-hydroxy ketone product was obtained in up to 82% enantiomeric excess. Deuterium-labelling studies demonstrated that the reaction is diastereospecific, with only the syn hydration product formed. So far, this diastereospecific and enantioselective reaction had no equivalent in conventional homogeneous catalysis.