Synlett 2008(5): 782-783  
DOI: 10.1055/s-2008-1032173
SPOTLIGHT
© Georg Thieme Verlag Stuttgart · New York

(Dichloroiodo)benzene (PhICl2)

Zhou Wu*
School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, P. R. of China
e-Mail: zwu@tju.edu.cn;

Further Information

Publication History

Publication Date:
26 February 2008 (online)

Biographical Sketches

Zhou Wu was born in Hebei Province, P. R. of China. She attended Hebei University of Science and Technology for her B.Sc. (2001) and Hebei University of Technology for her M.Sc. (2005) in chemical engineering. She is currently pursuing her Ph.D. under the supervision of Prof. Shende Jiang at Tianjin University. Her research is focused on the synthesis of fluorine-18 labelled radiopharmaceuticals for Positron Emission Tomography in molecular imaging and nuclear medicine.

Introduction

(Dichloroiodo)benzene (PhICl2) was first prepared in 1886; its chemistry then became an intensely studied topic because of its wide application as an effective chlorinating or oxidizing agent in various organic reactions. [1] As a chlorinating agent, (dichloroiodo)benzene can be applied not only to the addition of chlorine to alkenes, but also to the chlorination with other substrates, such as alkanes, ethers, esters, thioethers, ketones, sulfoxides, steroids, etc., with moderate to high yields. [1] [2] (Dichloroiodo)benzene can oxidize aldoximes and ketoximes to nitrile oxides [3] and ketones, [4] respectively in good yields. In this spotlight, recent applications using PhICl2 in organic syntheses are summarized.

Preparation

(Dichloroiodo)benzene was prepared by bubbling chlorine gas through a solution of iodobenzene in chlorinated solvents, [5] which had been applied to an industrial-scale preparation (Scheme [1] ). [6]

Scheme 1

Properties

(Dichloroiodo)benzene exists as yellow crystalline solid with mp 110-112 °C. It is not stable on long standing, which means that it is normally prepared and used fresh for subsequent applications.

Abstracts

(A) Alkynes can be effectively thiocyanated by the combination of PhICl2/Pb(SCN)2 in dichloromethane to yield the corresponding alkenes with high E/Z ratio. [7]
(B) A combination of PhICl2/KSCN can thiocyanate β-dicarbonyl compounds, phenols as well as anilines to the corresponding thiocyanato derivatives in dichloromethane. [8]
(C) PhICl2 can be used for the chloromethoxylation, iodomethoxylation, iodohydroxylation, and iodochlorination of alkenes under different conditions with good yields. [9] [10]
(D) Aliphatic primary and secondary alcohols can be oxidized to the corresponding aldehydes and ketones in good to excellent yields by the combination of PhICl2/2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPO)/pyridine in CHCl3. This oxidizing system has preference to oxidize secondary alcohols over primary ones. [11]
(E) Reactions of PhICl2 with 4-hydroxypyridin-2-ones in aq Na2CO3 gave an aryliodonium ylide that rearranged to 3-iodo-4-phenoxy­pyridinones. This operation can install both the iodine and aryloxy groups to the pyridinone nucleus. [12]
(F) PhICl2 is a good reagent for the oxidative chlorination of various metal complexes. [13] For example, treatment of dinuclear platinum(II) complexes as a mixture of isomers (the half-lantern and lantern complexes) with PhICl2 in dichloromethane gave the dichlorodiplatinum(III) lantern complex in excellent yield. [14]

Scheme 1