Iodonium imides

Imidoiodanes or iodonium imides, ArINR, are the I-N analogues of iodonium ylides and iodosylbenzene. The best known and widely used iodonium imide is Af-tosyliminophenyliodane (PhINTs), which has found synthetic application as a useful nitrene precursor under thermal or catalytic conditions in the aziridination of alkenes and the amidation reactions of various organic substrates. The chemistry of iodonium imides was reviewed by Dauban and Dodd in 2003 [623]. 

Preparation Aryliodonium imides 463 are usually prepared by the reaction of (diace-toxyiodo)arenes with the respective amides under basic conditions (Scheme 2.133) [623]. Most iodonium imides are relatively unstable at room temperature and their storage under an inert atmosphere at low temperature is recommended. Exothermic decomposition frequently occurs at the melting point of ylides and some of them were even claimed to be explosive [623]. 

Examples of the known iodonium imides, ArINR, include A-tosyl- [67,624-627], N-methanesulfonyl [628] and A-trifluoroacetyl derivatives [629]. A-(Trifluoroacetyl) and A-(methanesulfonyl) iminoiodanes are relatively unstable and explosive, while the tosylate derivatives are stable, crystalline compounds that can be stored for extended periods. 

Structural Studies Single-crystal X-ray structural data have been reported for the following iodonium imides (Figure 2.19) phenyl(iV-tosylimino)iodane (477) [67,635], mesityl(Ai-tosylimino)iodane... 

Figure 2.20 Primary and secondary bonding pattern in single-crystal X-ray structures of iodonium imides 477 and 478.

To a stirred suspension of 2-amino-1,4-naphthoquinone (173 mg, 1 mmol) in dichloromethane (15 ml) was added [hydroxy(tosyloxy)iodo]benzene (411 mg, 1.05 mmol). After 20 min, the yellow iodonium salt which separated was collected, washed with dichloromethane and dried (520 mg, 95%). This salt (547 mg, 1 mmol) was added to a cold aqueous solution of 2% sodium hydroxide (2 mmol). The mixture was stirred until the yellow colour turned red, about 20 min the precipitate was collected, washed with water and ether and dried to give 2-phenyliodonio-l,4-naphthoquinone-3-imide (263 mg, 70%), m.p. 115-117°C. 

The iodonium salt 193 derived from methyl acetoacetate behaves as an a-ketocarbene equivalent and adds to methyl ketones to give the dioxoles 194. Similar addition to C=S occurs for thioketones to give 195 and with CS2 to give the oxathiole-2-thione 196 (Scheme 18) <2002TL5997>. The corresponding diazo compound 197 reacts with succin-imide and a rhodium catalyst to give the spiro dioxole 198 <2006TL2643>. 

PI containing epoxy as side chain group was prepared by reacting epichlorohydrin with poly(hydroxy imide) in the presence of benzyl(trimethyl)ammonium chloride at 110-120 °C. Earlier, poly (hydroxy imide) was derived from 6FDA and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (AHHFP). Reaction scheme is given in fig. 30 [147]. Its photochemical reactivity was studied in the presence of diphenyl-iodonium-9,10-dimethylanthracene-2-sulfonate as photo-acid generator [148]. 

---