Elaborating On Heterocycles

Researchers have created an unexpectedly stable set of borylated dicarbonyl compounds that react to form borylated heterocyclic molecules that were previously difficult or impossible to make and that could be useful as building blocks in organic synthesis. The borylated dicarbonyls have multiple reactive groups in close proximity, leading chemists to think they would break down too quickly to be useful as reaction intermediates. But Andrei K. Yudin of the University of Toronto and coworkers have found they are stable and can undergo double condensations that result in heterocyclic ring formation (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201504271). The researchers make the dicarbonyl intermediates by combining photoredox catalysis and organocatalysis to couple brominated ketones with an N-methyliminodiacetic acid (MIDA)-boryl aldehyde. The stable dicarbonyls in turn react with nucleophiles to form MIDA-boryl pyrroles, furans, and pyridazines.