Singlet-oxygen generation in the catalytic reaction of dioxiranes with nucleophilic anions.
Nucleophilic anions such as Cl(-), I(-), Br(-), t-BuO(-), O(2)(-) and OH(-) efficiently catalyze the decomposition of dimethyldioxirane (DMD) and methyl(trifluoromethyl)dioxirane (TFD). Singlet oxygen ((1)O(2)) is formed in these catalytic reactions, as demonstrated by the characteristic infrared chemiluminescence (IR-CL) at 1268 nm. The yield of (1)O(2) generation, measured by the IR-CL method, lies in the range between 2 and 98%, which depends on the particular anion employed. For the bromide ion, the catalytic decomposition of the dioxirane is in competition with the oxidation of Br(-) to elemental bromine.
Mechanism of singlet oxygen generation during catalytic decomposition of methyl(trifluoromethyl)dioxirane by chloride ions
The mechanism of the chloride ion-induced catalytic decomposition of methyl(trifluoromethyl)dioxirane in trifluoroacetone was studied at the MP4//MP2/6-31+G(d) level of theory. The solvated chloride ion interacts with dioxirane to form an ion-dipole pair, which is transformed into the key intermediate ClO—C(Me)(CF3)—O− acting as a chain carrier in the catalytic decomposition of dioxirane. The generation of singlet oxygen occurs during the transformations of this intermediate on the singlet potential energy surface.
Catalytic removal of tert-butyldimethylsilyl (TBS) ether by PVP-I
Abstract A mild, efficient and rapid protocol the deprotection of alcoholic TBDMS ethers using PVP-1 as catalyst in methanol, the procedure of deprotection of various TBDMS ethers were found to be very convenient, easy work-up, high yielding.