Solvent-free iodination of organic molecules using the I(2)/urea-H(2)O(2) reagent system.
Introduction of iodine under solvent-free conditions into several aromatic compounds activated toward electrophilic functionalization was found to proceed efficiently using elemental iodine in the presence of a solid oxidizer, the urea-H(2)O(2) (UHP) adduct. Two types of iodo-functionalization through an electrophilic process were observed: iodination of an aromatic ring, and side-chain iodo-functionalization in the case of arylalkyl ketones. Two reaction routes were established based on the required substrate : iodine : oxidizer ratio for the most efficient iodo-transformation, and the role of UHP was elucidated in each route. The first, requiring a 1 : 0.5 : 0.6 stoichiometric ratio of substrate to iodine to UHP, followed the atom economy concept in regard to iodine and was valid in the case of aniline, 4-t-Bu-phenol, 1,2-dimethoxy benzene, 1,3-dimethoxy benzene, 1,2,3-trimethoxy benzene, 1,2,4-trimethoxy benzene, 1,3,5-trimethoxy benzene, 1-indanone and 1-tetralone. The second reaction route, where a 1 : 1 : 1 stoichiometric ratio of substrate : I(2) : UHP was needed for efficient iodination, was suitable for side-chain iodo-functionalization of acetophenone and methoxy-substituted acetophenones. Moreover, addition of iodine to 1-octene and some phenylacetylenic derivatives was found to proceed efficiently without the presence of any oxidizer and solvent at room temperature.
Pavlinac
Jasminka
J
Laboratory for Organic and Bioorganic Chemistry, 'Jozef Stefan Institute', Jamova 39, 1000 Ljubljana, Slovenia.
Zupan
Marko
M
Stavber
Stojan
S
D006841:Hydrocarbons, Aromatic / Q000138:chemical synthesis* / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007455:Iodine / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013237:Stereoisomerism; D014508:Urea / Q000737:chemistry*
D006841:Hydrocarbons, Aromatic; D014508:Urea; D007455:Iodine; D006861:Hydrogen Peroxide