Observations related to the preparation of 2-phenyliodoniobenzoate

Abstract

The barrier to ring inversion for 1 is slightly smaller than those of 1,2-dithiane, 11.6 kcal/mol,6 and 1,3dithiane, 10.4 kcal/mol,6 although it would hardly be tenable to draw very detailed conclusions concerning dithiane itself from the results for 1. On the basis of the fluorine chemical-shift differences at -90°, which compare reasonably well with those for noninverting (or slowly inverting) gera-fluorocyclohexanes,7 we have assumed that the preferred conformation of 1 is a chairpossibly strongly puckered as for 1,4-dithiane.8Registry No.-1,710-65-6.Acknowledgment.-We are grateful to Mr. J. E. Leininger for assistance with the computing.

Hypervalent (tert-Butylperoxy)iodanes Generate Iodine-Centered Radicals at Room Temperature in Solution: Oxidation and Deprotection of Benzyl and Allyl Ethers, and Evidence for Generation of α-Oxy Carbon Radicals

“…Thus, 1a (2 equiv)/K 2 CO 3 (4 equiv)/25 °C/PhH/N 2 constituted our standard conditions. When the p -nitroperoxyiodane 1b , prepared from 2-iodosyl-5-nitrobenzoic acid by the ligand exchange reaction with tert -butyl hydroperoxide, was used instead of 1a , the oxidation rate was slightly retarded (see Figure ).

2 Time courses for the oxidation of 2d with 1 in the presence of K 2 CO 3 in benzene under nitrogen. Symbols are as follows: (·) 1a (1 equiv)/K 2 CO 3 (2 equiv)/25 °C, (○) 1a (2 equiv)/K 2 CO 3 (4 equiv)/25 °C, (×) 1a (3 equiv)/K 2 CO 3 (6 equiv)/25 °C, (▴) 1a (2 equiv)/K 2 CO 3 (4 equiv)/50 °C, (□) 1b (2 equiv)/K 2 CO 3 (4 equiv)/25 °C.

…”

“…Synthesis of 1-( tert -Butylperoxy)-5-nitro-1,2-benziodoxol-3(1 H )-one (1b). To a stirred suspension of powdered 1-hydroxy-5-nitro-1,2-benziodoxol-3(1 H )-one (5.56 g, 18.0 mmol), prepared from 2-iodobenzoic acid by the reaction with concentrated sulfuric acid and fuming nitric acid, and tert -butyl hydroperoxide (3.38 mL of 80% solution in di- tert -butyl peroxide, 27.0 mmol) in 100 mL of chloroform was added dropwise BF 3 −Et 2 O (2.22 mL, 18.0 mmol) at room temperature under nitrogen, and the mixture was stirred for 3.5 h. The reaction mixture was quenched with water, and the resulting precipitate was removed by filtration. The mixture was extracted with dichloromethane.…”

Organohypervalent heterocycles

“…436,443–445 Arylbenziodoxoles have been shown to possess a zwitterionic structure, as evidenced by the presence of a short internal interaction between iodine and oxygen atoms. 436–438,440–443 Further, the average distance of the intramolecular I⋯O bonds (2.5 Å) is longer compared to the average covalent I–O bond length (2.14 Å); 446,447 however, shorter than the sum of van der Waals radii for iodine atom and oxygen atoms (3.5 Å), 448 indicating a significant increase in the ionic nature of this bond.…”

“…Arylbenziodoxoles 170 can be easily prepared from the appropriate 2-iodobenzoic acids 171 and substituted benzenes [431][432][433][434][435][436][437][438][439] (Scheme 40). Moreover, these compounds can also be obtained from suitable hypervalent iodine reagents through ligand exchange reaction.…”

Iodonium Salts as Benzyne Precursors

“…[30] Phenylbenziodoxole and substituted phenylbenziodoxoles have been employed as the effective aryne sourcesinthe pres-ence of common benzyne trapping compounds such as antracene, 1,3-diphenylisobenzofuran, and tetracyclone compounds. [44,55,57,[61][62][63][64] For example, the reaction of antracene 17 using 5-nitro-2-phenylbenziodoxole 18 as aryne speciesprecursor under reflux conditions gave the corresponding 2-nitrotriptycyne 19 in 43 %y ield, [61] and the reactiono ft etracyclone compounds 20 using phenylbenziodoxole 5 in g-butyrolactone at reflux conditions led to the corresponding tetraphenylnaphthalenecompounds 21 in 56-79% yields (Scheme 7). [55] 1-Phenylbenziodoxole 5 is ap articularly useful reagent for the reactions leading to new carbon-heteroatom bond formation.…”