The Conundrum Of Odourless Kahweofuran, A Roasting "Flavour" Of Coffee

A new synthesis of the dihydrothieno [2,3-c]furan Kahweofuran, isolated from coffee extracts, reveals it probably does not possess the intense and Violent' sulfurous odour previously ascribed to it. We speculate that trace amounts of thiol compound(s) present as impurities in the original isolate and perhaps in other synthetic samples are instead responsible. Key steps in the present approach are a 5-endo-dig iodocyclisation to establish the furan ring and a final, highly efficient copper-catalysed intramolecular C-S bond formation of the intermediate 3-iodofuran. (C) 2020 Elsevier Ltd. All rights reserved.