TMSPs

Et4N F , CH3CN, 48 h, reflux. TMSF and allene are formed in the cleavage reaction. These conditions are not compatible with phenyl phosphates, which are cleaved preferentially with fluoride.Cleavage of a bis TMSP phosphate results in the cleavage of only one of the TMSP groups. 

Goals and five limitations in conjunction with the development of selective catalytic homogeneous oxidation systems are evaluated. Systems are presented that address several of the problems or goals. One involves oxidation of alkenes by hypochlorite catalyzed by oxidatively resistant d-electron-transition-metal-substituted (TMSP) complexes. A second involves oxidation of alkenes by H2O2 catalyzed by specific TMSP complexes, and a third addresses functionalization of redox active polyoxometalate complexes with organic groups. 

The robustness of TMSP-type catalysts allows one to address many of the limitations regarding the development of optimal catalysts for homogeneous selective oxidation, including the five general limitations articulated above (1) inadequate... 

We report here three studies that address three separate but significant issues in the emerging area of selective catalytic oxidation by TMSP-type complexes. The first study establishes for the first time that some TMSP complexes are compatible with basic oxidants and basic conditions. The second study reports the first oxidation, in this case selective alkene epoxidation, by the economically and environmentally desirable oxidant, aqueous hydrogen peroxide, catalyzed by TMSP complexes. The third study demonstrates that redox active polyoxometalates can be derivatized with alcohols in a manner that should prove useful for fabricating future generations of more sophisticated and selective TMSP catalysts. 

Table II. Oxidation of Cyclohexane by Hypochlorite Catalyzed by Two TMSP Complexes...

The use of benzene as a solvent eliminates the chlorinated organic products in Table II. This point and the products in the table are consistent with radical abstraction (hydrogen atom transfer) from the substrate, cyclohexene, by the high valent (and likely oxometal) intermediate form of the TMSP complexes, followed by chlorine abstraction from the solvent by intermediate organic radicals. Separation and analysis of the two phases after the reaction reveals that the polyoxometalate is intact. 

Alkene Epoxidation by H2O2 Catalyzed by TMSP Complexes. The... 

Table III. Oxidation of Cyclohexene by H2O2 Catalyzed by TMSP...

Some TMSP systems that preclude i-oxo dimer formation and exhibit the right proton-linked redox potentials should facilitate selective catalytic aerobic oxidation such as that defined in equations 3-6. Selective catalytic aerobic oxidation has yet to be achieved, however. The few TMSP systems examined thus far in conjunction with C>2-based oxidations function as redox initiators of autoxidation. 

Transition metal-substituted POMs (TM-SPs) can be considered as the largest subclass of polyanions [6]. Within the class of TMSPs, the sandwich-type compounds represent the largest family. In short, sandwich-type POMs are formed by the fusion of two trivacant a-XW9 034" ... 

Two examples are selected to describe and discuss the electrocatalytic reduction of di oxygen, the first one with a TMSP [161] and the second one with a sandwich-type complex [162]. The discussion reflects the questions encountered also with usual plenary POMs. 

Substituted polyacetylenes has been most intensively examined as gas-permeable materials aiming at practical application. These studies are motivated by the extremely high gas permeability of poly(TMSP), ... 

TMSP is also active for paraffin hydroxylation. Figure 63 is a summary indicating the number of turnovers of a variety of oxo transfer catalysts before catalyst decomposition (320b). When tert-butyl hydroperoxide is used as an... 

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