Phenyliodine dichloride

Photoinitiated free-radical chlorination of (10) using phenyliodine dichloride is directed exclusively to the C(9) position, probably as a result of the conformation of the steroid placing the C(l) complexed to the template iodine atom close to the C(9) hydrogen. Dehydrochlorination then places a double bond in the C(9)-C(l) position. 

In the course of carrying out the benzophenone photochemistry described in the previous section, we noted that the use of CCI4 as solvent led to the formation of some chlorinated steroid products. Therefore we examined such halogenations further [36], and found that the simple free-radical chlorination of cholestanyl acetate with phenyliodine dichloride afforded the 9-chloro- and 14-chlorosteroids as the major products. Similar results were seen in bromination by bromotrichloromethane. We extended such selective radical halogenations to suppress reactions other than at C-9 and C-14 by appropriate substituent effects, but more significantly we used tethers to achieve essentially complete selectivity in the halogenations [36]. 

We irradiated a solution of phenyliodine dichloride with the w-iodobenzoate ester 12 of 3a-cholestanol and found that C-9 chlorination occurred selectively, while no such selectivity was seen without the iodine atom on the benzoate ester [37]. Various controls established that we were not simply converting the attached iodoaryl template to its... 

We showed that radical relay in the presence of phenyliodine dichloride but with an excess of CBr4 afforded the bromosteroid, with bromine at the point that is normally chlorinated [55]. When (SCN)2 was the additive, rather than CBr4, an SCN group was formed [55]. The mechanism shown (Scheme 6-8) involves a bromine atom transfer to... 

Phenylindanone, 618 2-Phenylindole, 161 2-Phenylindoles, 456 2-Phenylindoxyl O-benzoate, 161 Phenyliodine dichloride, 298-300 Phenyliodine(lII) difluoride, 300 Phenyiiodine(III) ditrifluoroacetate, 301 Phenyl isocyanide dichloride, 458 a-Phenyl ketones, 234 Phenylmercuric acetate, 458 2-Phenylmesitylene, 59... 

This is the largest group of compounds and, although many examples have been prepared since the original report of phenyliodine(III) dichloride a century ago,57 few crystal structures have been determined. The compounds have been classified as shown in Table 5. 

Phenyliodine(III) difluoride, C6H5IF2 (1). The simplest route to this hypervalent reagent is the reaction of iodobenzene dichlorides with aqueous hydrofluoric acid in the presence of HgO (yellow). The p-f-butyl derivative of 1 is a stable, crystalline solid. 

The characteristic T-shaped coordination is found for compounds with one carbon and two heteroatom ligands. The simplest structure is that of phenyliodine(III) dichloride with I—Cl bond distances of 2.54 A and Cl—I—C angles of 86°. In general, in the other examples for which structures have been determined, the corresponding angles are less than 90°. Secondary bonding is important in the overall packing of these compounds and has been fully analyzed for two examples. ... 

Several procedures exist for the synthesis of a-chloro thioethers and sulfoxides. The solid iodobenzene dichloiide [phenyliodine(III) dichloride] reagent is a convenient source of positive chlorine, and the lipophilic iodobenzene by-product can be recycled. Colonna and cowoikers have reported reactions of sulfoxides with iodobenzene dichloride and investigated the stereochemistry of a-chloro sulfoxides obtained und various conditions. ... 

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