Stereoselective hydrogenation of methylcyclohex-2-ene-1,4-diols used in the synthesis of ampelomins and deoxy-carbasugars

A gram-scale synthesis of β-L-carbafucose for engineering antibody glycans

Afucosylated antibodies often exhibit superior properties compared to their fucosylated counterparts including, among others, enhanced antibody-dependent cell cytotoxicity (ADCC). While several recombinant and biochemical strategies have been identified for generating afucosylated antibodies, small molecule metabolic inhibitors provide a potentially more straightforward option. We recently reported that β-L-carbafucose is an inhibitor of antibody fucosylation and is not incorporated into the antibody glycans. To support the further study of β-L-carbafucose, a gram-scale synthesis was needed. Here, we report our investigation of three distinct synthetic routes, including a highly efficient chromatography-free synthesis. Further, we demonstrate multi-gram production of afucosylated Herceptin (Trastuzumab®) in 10 L bioreactors using β-L-carbafucose. We expect this new synthetic process will support the widespread adoption of β-L-carbafucose for producing afucosylated antibodies for discovery and development purposes.

Readily accessible azido-alkyne-functionalized monomers for the synthesis of cyclodextrin analogues using click chemistry

A set of linear and cyclic oligomers were synthesized starting from a suitable azido-alkyne monomer through click oligomerization. The synthesis of these monomers starting from bromobenzene features an enzymatic dihydroxylation...

Chemoenzymatic Total Synthesis and Structural Revision of Ampelomins B, D, E, and epi-Ampelomin B

Enantioselective synthesis of ampelomin B and epi-ampelomin B, D, and E was accomplished starting from toluene, through a chemoenzymatic sequence, in which stereoselective hydrogenation, Mitsunobu reaction, and regio- and stereoselective nucleophilic opening of an epoxide were used as the main transformations. Structural revision and absolute configuration of the natural compounds were carried out.

Asymmetric synthesis of Ampelomin A and ent-Epiampelomin A

We synthesized the naturally occurring carbasugar ampelomin A and its epimer from a common starting material. The enantiomerically pure starting material was obtained by base-catalyzed asymmetric Diels-Alder reaction of 3-hydroxy-2-pyrone and chiral acrylate. The total yield of ampelomin A was 14% in seven synthetic steps. The key step of the synthesis of ampelomin A was inversion of the stereochemistry at the C-6 position, which was achieved by stereoselective catalytic hydrogenation of the corresponding methylidene group. Further synthesis of the epimer was straightforward, because all stereogenic centers had already been introduced on the starting material; the total yield was 44% in four synthetic steps. Both the final products were obtained in pure form without contamination with undesired isomers. The reported (1)H NMR chemical shift of the C-7 methyl protons and the H-5axial coupling pattern of natural ampelomin A were inconsistent with those of our synthetic product. After careful comparison of the spectra and examination of the stable conformation obtained through MM2 calculations, we present revised NMR data for ampelomin A.