The aryl-λ3-iodane, [hydroxy((bis(2,2,2-trifluoroethoxy)phosphoryl)oxy)iodo]benzene (1), was prepared from [hydroxy(tosyloxy)iodo]benzene and sodium bis(trifluoroethyl) phosphate in methanol. This novel iodine (III)-phosphate reagent was employed for the conversion of acetone to its α-bis(trifluoroethyl) phosphate derivative, and for ligand-transfer oxidations of various alkyl iodides to the corresponding alkyl bis(trifluoroethyl) phosphates.
The use of 1 for oxidative rearrangements of arylalkenes to geminal-bisphosphate esters was also explored. Samples of 1 and the known diphenyl analogue, [hydroxy((bis(phenyloxy)phosphoryl)oxy)iodo]benzene were submitted for single crystal X-ray analysis.
Equilibrium constants (KD) for the hydration of α-(mesyloxy)acetone, α-((bis(methoxy)phosphoryl)oxy)acetone, and α-((bis(ethoxy)phosphoryl)oxy)acetone in D2O at 25, 35, 45, and 55 °C were determined by 1H NMR analysis. Plots of log KD versus T-1 enabled calculations of the enthalpy (H) and entropy (S) of hydration for all three substrates. Hydration constants of the ketol phosphates in D2O (KD) and H2O (KH) at 25 °C were also determined by 31P NMR analysis. The hydration constants were employed with reported linear free energy relationships for estimates of Taft polar substituent constants (σ*) of the (mesyloxy)methyl and bis((alkoxy)phosphoryl)oxy)-methyl groups, and equilibrium constants for hydroxide addition to the ketol phosphates. Hydration of the α-bis(trifluoroethyl) phosphate derivative of acetone in D2O was accompanied by spontaneous hydrolysis of the ketol phosphate to two sets of products. The mechanistic origin of the phosphate products was examined by conducting the hydrolysis in D2O mixed with 18O-labeled H2O.
4,4-Dimethyl-2-nitromethyl-2-(diacetoxyiodo)biphenyl was synthesized from 4,4-dimethyl-2-iodobiphenyl and submitted for single crystal X-ray analysis. A key step in the synthetic procedure was ring-opening of a cyclic iodonium salt with nitromethane anion. A preliminary 1H NMR study of the dynamic behavior of the biaryl-3-iodane was conducted and its cyclization with p-toluenesulfonic acid to a dibenziodonium salt was demonstrated. Efforts to convert the diacetoxyiodane and the corresponding iodo compound to an iodine (III) heterocycle containing the 9-iodaphenanthrene ring system were unsuccessful.