BUILDING-BLOCKS FROM SUGARS - PART. 23 - HYDROPHILIC 3-PYRIDINOLS FROM FRUCTOSE AND ISOMALTULOSE

Brief exposure to bromine in water-methanol at 0 OC smoothly and effec tively converts furfurylamines with hydroxymethyl (5) or glucosyloxyme thyl substituents (16) into the respective 6-substituted 3-pyridinols 9 and 19, whereas the N-methyl-furfurylamines 10 and 17 elaborate the N-methyl-pyridinium betaines 13 and 22. Combination of this multistep one-pot reaction with the large scale-feasible generation of hydroxyme thylfurfural (4) from D-fructose and its O-glucosyl analog 15 from iso maltulose, together with their ready conversion into furfurylamines by reductive amination, opens up a preparatively satisfactory, 3-step '' reaction channel'' from inexpensive sugars to hydrophilic 3-pyridinols , of interest as intermediate chemicals for drugs of the pyridostigmin e type and agrochemicals. (C) 1998 Elsevier Science Ltd. All rights re served.