Ozonolysis of Alkynes to a-Diketones. Synthesis of AI-2

Scientific Achievement:

Depiction of bioluminescent AI-2 synthesized by ozonolysis of alkynes. At high extracellular concentrations, AI-2 induces bioluminescence in Vibrio campbellii.

This work provides a general entry to α-diketones and a direct route to furanosyl borate diester (AI-2), a signal molecule for inter-species quorum sensing. This new synthetic route enables studies to assess the role of AI-2 in the rhizosphere microbiome.

Significance and Impact:

The conventional approach to α-diketones employs expensive and toxic metals. The new method uses no metals and proceeds readily at sub-ambient temperatures.

Research Details:

–A range of alkynes can be converted into α-diketones.
–Esters, aromatics and alcohols are compatible with the mild conditions.
–Even unstable diketones such as 4,5-dihydroxypentane-2,3-dione, the direct precursor to AI-2, can be produced.

Alterman, J. L.; Vang, D.X.;  Stroud, M.R.; Halverson, L.J.; Kraus. G.A.  Ozonolysis of Alkynes – A Flexible Route to α-Diketones.  Synthesis of AI-2 Organic Letters, 2020, 0000. DOI: 10.1021/acs.orglett.0c02182.