To circumvent protecting groups, the site-selective modification
of unprotected glycosides is intensively studied. We show that site-selective
oxidation, followed by treatment of the corresponding trityl hydrazone
with
tert-
butyl hypochlorite and a H atom donor provides
an effective way to introduce a chloride substituent in a variety
of mono- and disaccharides. The stereoselectivity can be steered,
and a new geminal dichlorination reaction is described as well. This
strategy challenges existing methods that lead to overchlorination.
In Mycobacterium tuberculosis,m ycolic acids and their glycerol, glucose,a nd trehalose esters ("cord factor") form the main part of the mycomembrane.D espite their first isolation almost acentury ago,full stereochemical evaluation is lacking, as is as calable synthesis required for accurate immunological, including vaccination, studies.H erein, we report an efficient, convergent, gram-scale synthesis of four stereo-isomers of amycolic acid and its glucose ester.Binding to the antigen presenting protein CD1b and Tc ell activation studies are used to confirm the antigenicity of the synthetic material. The absolute stereochemistry of the syn-methoxy methyl moiety in natural material is evaluated by comparing its optical rotation with that of synthetic material.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under https://doi.
In Mycobacterium tuberculosis, mycolic acids and their glycerol, glucose, and trehalose esters (“cord factor”) form the main part of the mycomembrane. Despite their first isolation almost a century ago, full stereochemical evaluation is lacking, as is a scalable synthesis required for accurate immunological, including vaccination, studies. Herein, we report an efficient, convergent, gram‐scale synthesis of four stereo‐isomers of a mycolic acid and its glucose ester. Binding to the antigen presenting protein CD1b and T cell activation studies are used to confirm the antigenicity of the synthetic material. The absolute stereochemistry of the syn‐methoxy methyl moiety in natural material is evaluated by comparing its optical rotation with that of synthetic material.
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