Efficient total synthesis of iso-cladospolide B and cladospolide B

Chiral Cobalt-Salen Complexes: Ubiquitous Species in Asymmetric Catalysis

Since the discovery of their extraordinary reactivity in the hydrolytic kinetic resolution of terminal epoxides about twenty years ago, chiral cobalt-salen complexes have been shown to be essential for many other asymmetric catalytic reactions. This account summarizes the inspiring works dedicated to the discovery of their new reactivity and their mode of action, as well as the new processes towards the optimization of their cooperativity for bimetallic activation and the implementation of their effective immobilization, including also our contribution on these topics.

Twelve-membered macrolactones: privileged scaffolds for the development of new therapeutics

Natural products commonly produced as secondary metabolites of various plants and micro-organisms represent a diverse chemical space of compounds. The diversity of natural products makes them an attractive target for interrogation by both chemists and biologists alike. Indeed, the study of 12-membered macrolactones has already led to the discovery of lead drug compounds and new biological targets, which has motivated the development of diverted total synthetic routes to libraries of analogs. This review explores the discovery, biological characterization, and synthesis of several 12-membered macrolactones, exploiting examples that underscore their importance in the drug discovery field. It is our hope that this review will motivate further interest in this class of natural products, a group of molecules that we think merit the classification of 'privileged scaffolds' within the medicinal chemistry community, to further investigate and develop novel compounds with promising bioactivity.

A flexible and unified strategy for syntheses of cladospolides A, B, C, and iso-cladospolide B

A simple, efficient and flexible strategy for the syntheses of cladospolides A-C and iso-cladospolide B is reported here. This strategy involves Julia-Kocienski olefination and Yamaguchi macrolactonization as key steps, starting from either d-ribose or suitable tartaric acid esters. Although our initial efforts towards cladospolide A involving a ring closing metathetic approach were not successful, changing the mode of ring closure and the use of Julia-Kocienski olefination for the construction of the key intermediate solved this issue and paved the way for the completion of total syntheses of this class of natural products.

Synthesis of (+)-Cladospolide C

(+)-Cladospolide C was synthesized in eight steps with 5% total yield, using methyl acrylate, (3R,4R)-1,5-hexadiene-3,4-diol, and (6R)-6-hepten-2-ol as the starting materials. Two cross-metathesis reactions and Yamaguchi esterification were applied to assemble the three units into (+)-Cladospolide C. Unsuccessful routes using ring-closing metathesis are also discussed.

Palladium-catalyzed asymmetric allylic alkylation of meso- and dl-1,2-divinylethylene carbonate

The palladium-catalyzed asymmetric allylic alkylation of a 1:1 mixture of dl- and meso-1,2-divinylethylene carbonate is reported. For the first time, both the ionization and nucleophilic addition steps of the catalytic cycle act as enantiodiscriminating steps to give a single product in high enantiomeric excess. The reactions proceed in >98% ee to efficiently generate useful chiral building blocks from acrolein. The absolute and relative configurations of iso-cladospolide B and 11-epi-iso-cladospolide B were verified by total synthesis, solving an apparent discrepancy in the literature.