Electrostatic Activation of Hypervalent Organo‐Iodine Compounds: Bis(onio)‐Substituted Aryliodine(III) Salts

Abstract

The new approach for the preparation of P,P-disubstituted pyrroles presented here opens up a rational, and multifacetted direct route to porphyrins with a three-dimensionally structured periphery. This has led to the preparation of the first biconcave metalloporphyrins, whose frameworks promise interesting catalyst properties.E-xperinien f a1 Procedure 1: Acetylcnedicarbonitrile (234 mg, 3.08 mmol) in benzene ( 5 mL) was added dropwise over 4 h (under N2) to a heated (XO'C) suspension of 2,3,6,7-tetramethylanthracene (452 mg. 1.93 mmol) [IS] in benzene ( 5 mL). The reaction mixture was heated under retlux for an additional 10 h. After cooling and concentration of the mixture. column chromatography (silica gel, CH,Cl,/petroleum ether 1/1) and crystalliration from CH,CI, yielded 562 mg (1.81 mniol, 94%) I. 2: DlBAH (12 mmol. 1 M in hexane) was treated with 1 (0.60 g. 1.93 mmol) in dry CH2CI, (20 mL) under N, at ~ 20 C and stirred. The mixture was stirred at -20°C for 3.5 h. treated with aqueous citric acid ( 0 . 5~. 16 mL) and diluted with aqueous citric acid (0.5 M. 12 mL) and CH,CI, (12 mL) at room temperature. The organic phase was concentrated and purified by column chromatography (silica gel, CH,CI,:petroleum ether I l l ) . The colorless pyrrole 2 (190.5 mg, 0.64 mmol) crystallized from CH2C12/hexane (1 ' 5 ) in 33% yield. 3 . A solution of2 181 mg. 0.27 mmol) in CH2CI, (0.6 mL) was treated under N, with CH,OH (0.84 mL). aceticacid (78 pL). and 30% formaldehyde solution (111 pL). The mixture has protected from light, stirred for 7 d at room temperature under N,, and then concentrated. The residue was dissolved in benzene (2 mL) under N, and treated Mith dichlorodicyanobenzoquinone (DDQ) (42.3 mg, 0.18 mmol) in ben-Lene (4 mL). After2.5 h a t room temperature, the solution wasdiluted with CH,CI, (7 mL) and shaken with phosphate buffer (pH 7) (0.

Synthesis and Properties of Dinuclear Complexes with a Photochromic Bridge: An Intervalence Electron Transfer Switching “On” and “Off”

“…After systematic search of chemical oxidation procedures, we chose an oxidation by the triflate salt of bis(pyr- iting an intervalence absorption in the 1000Ϫ1500 nm range; total concentration: 5.7⋅10 Ϫ5 mol⋅L Ϫ1 ; path length: 1 cm; 1: initial spectrum; 2: spectrum at half-oxidation; 3: spectrum of the fully oxidized solution idyl)phenyliodonium, formally containing iodine(III). [30] Interestingly, in our case, this reagent reacted instantaneously, did not generate acidic species (which would be harmful for the cyclometalated moieties), and the by-products are merely iodobenzene and pyridine. Finally, both the reagent and by-product (iodobenzene) are almost nonabsorbent in the visible and near-IR regions.…”

“…The reported preparation [30] starts from iodobenzene diacetate. However, the commercial reagent gave unsatisfactory results.…”

“…[37] Then iodobenzene diacetate was converted into the triflate salt of bis(pyridyl)-phenyliodonium by reaction with trimethylsilyl trifluoromethanesulfonate. [30] The obtained whitish solid was kept under argon at Ϫ20°C.…”

A Practical One‐Pot Synthesis of Positron Emission Tomography (PET) Tracers via Nickel‐Mediated Radiofluorination

“…This was, for example, the reason for the high statistical deviations of RCC values that were observed in the optimization experiments. In an attempt to overcome this problem, we prepared several hypervalent iodine compounds, such as 5 , and iodosylarenes 6 a,b as less moisture‐sensitive alternatives to 2 (Figure ). However, application of these compounds as oxidants did not afford incorporation of 18 F.…”

Reactions of Trivalent Iodine Reagents with Classic Iridium and Rhodium Complexes

“…[6,12] These reagents were first synthesized by Weiss in 1994 and later investigated by Zhdankin. [13,14] These dicationic I III reagents typically simultaneously oxidize the transition metal and deliver the neutral ligands, allowing the isolation of charged metal complexes. The oxidation of compound 1 by [PhI(L) 2 ][OTf] 2 (2R) resulted in an unexpected outcome, as shown in Scheme 2.…”