Progressive Direct Iodination of Sterically Hindered Alkyl Substituted Benzenes
Stojan Stavber*, Petra Kralj, Marko Zupan
*Laboratory for Organic and Bioorganic Chemistry, ‘Joef Stefan' Institute
and Department of Chemistry, University of Ljubljana, Jamova 39, 1000 Ljubljana,
Slovenia, Email: stojan.stavber
ijs.si
S. Stavber, P. Kralj, M. Zupan, Synthesis, 2002, 1513-1518.
DOI: 10.1055/s-2002-33339
Abstract
Benzene derivatives bearing at least one bulky alkyl group (i-Pr or t-Bu) were selectively and effectively iodinated using elemental iodine activated by Selectfluor. Up to three iodine atoms were progressively introduced at the most electron-rich and sterically less hindered position on the benzene ring.
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Details
The document discusses the selective and effective iodination of benzene derivatives bearing bulky alkyl groups (i-Pr or t-Bu) using elemental iodine activated by SelectfluorTM (F-TEDA-BF4). The process introduces iodine atoms progressively at the most electron-rich and sterically less hindered positions on the benzene ring, with a maximum of three iodine atoms being added to a molecule. The iodination method is valuable for synthesizing aromatic iodides, which are crucial in carbon–carbon bond formation and have applications in drugs, diagnostics, and imaging. The study highlights the advantages of using the I2/F-TEDA-BF4 system, such as high regioselectivity and efficiency under mild conditions, and the consumption of both iodine atoms from elemental iodine. However, the method requires an excess of the reagent for multiple iodinations, and sterically strained molecules pose limitations. The document provides detailed experimental procedures, reaction conditions, and yields for various alkyl-substituted benzene derivatives, demonstrating the method's effectiveness and limitations. The research was supported by the Ministry of Education, Science, and Sport of Slovenia, and the findings contribute to the broader field of iodoorganic chemistry.
Key Words
iodination, sterically hindered benzenes, Selectfluor
ID: J66-Y2002-1580
