Arsenic compounds, aryl— from

Recent progress on the use of hypervalent iodine reagents for the construction of heteroatom-heteroatom bonds is reviewed. Reactions of aryl-A3-iodanes with heteroatom substrates derived from third-row elements and beyond are considered first, and an unusual example of heteroatom-heteroatom bond formation with diaryliodonium salts is then discussed. Finally, the use of sulfonylimino(aryl)iodanes for imidations of phosphorus, sulfur, selenium, and arsenic compounds, including enantioselective transformations (S,Se), and alternate hypervalent iodine approaches to N-sulfonylsulfilimines and N-sulfonylarsinimines are summarized. 

The use of hypervalent iodine reagents for heteroatom-heteroatom bond forming reactions is well established in the context of classical oxidation chemistry [1-11]. For example, oxidations of anilines to azobenzenes, thiols to disulfides, and sulfides to sulfoxides with aryl-A3-iodanes were documented decades ago [1-5]. During the last ten years, particular attention has also been given to oxidative transformations of compounds derived from heavier elements, including the interception of reaction intermediates or initially formed products with external nucleophiles. A second important development is the utilization of sulfonyliminoiodanes, ArI = NS02R, for heteroatom-nitrogen bond formation, especially for imidations of sulfur, selenium, phosphorus and arsenic com-... 

From the determination of the molecular refractions of a large number of organic compounds containing tervalent arsenic, the atomic refraction of arsenic in each compound has been calculated,10 the values obtained varying from 9-2 to 14-39. Hydrogen, chlorine and alkyl groups in an arsine exert about the same influence on the atomic refraction of arsenic, but replacement of any of these by aryl groups causes an increase in the atomic refraction. The opposite effect results from substitution by a cyanide, oxalate or alkoxyl radical. 

Various alkyl and aryl substituted pentaorganoarsenic compounds are known - . Most of these have been synthesized by transmetallation from Grignard reagents or organo-lithium reagents to arsenic centers. 

Several of the approaches to fully conjugated systems are also applicable to the synthesis of arsenic-containing dihydro derivatives. Of these, 3-arsolenes are common, whereas the only 2-arsolene synthesis occurs by isomerization. Benzo derivatives are also known. These methods allow preparation of compounds of different arsenic functionality (e.g., As-Cl, /fs-alkyl, 45-aryl), so different systems may be prepared by interconversion from one type of functionality to another. Stibolenes and bismolenes are still unknown. 

Arsenic hydrides are useful sources of this t)rpe of compound, reacting with sodium in liquid ammonia 215) or tetrahydrofuran 288), with potassium in dioxane or benzene 218), and with lithium, lithium alkyls and aryls, lithium alkoxides, lithium amides in various solvents 218,280a, 287a). Derivatives such as (C6Hs)2AsK and C HsAsHK can be isolated from dioxane as solvated crystals 163,218). 

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