TPAP Tetra-«-propylammonium

From the study of a microbially mediated oxidation of arteether 28b, sufficient quantities of 7a-hydroxy 180 and 15-hydroxy derivatives 182 were obtained to employ them as intermediates for the preparation of fluorinated compounds. The hydroxyl groups were oxidized to the corresponding aldehyde 187, or ketone 188, with catalytic quantities of tetra- -propylammonium perruthenate (TPAP) in the presence of excess iV-methylmorpholine A -oxide. On reaction with DAST, 187 and 188 were converted into the corresponding geminal difluoro derivatives, 189 (63%) and 190 (42%). In addition to 190, a monofluoro olefin 191 was obtained in 25% yield from 188 on reaction with DAST <1995JME4120>. 

TPAP Tetra-n-Propylammonium Perruthenate Pr4N+Ru04 ... 

A milestone in the routine employment of perruthenate in the oxidation of alcohols was established with the publication by Griffith, Ley et al. in 1987 on the catalytic use of tetra- -propylammonium perruthenate (TPAP).11 The presence of the tetra- -propylammonium cation renders this compound soluble in apolar media and allows the existence of a high concentration of perruthenate ion in organic solvents. The tetra- -propylammonium perruthenate is easily prepared and can be employed catalytically in CH2CI2 solution in the oxidation of alcohols to ketones and aldehydes, using /V-methyl morpholine A-oxide (NMO) as the secondary oxidant. 

W. P. Griffith, S. V Ley, TPAP Tetra-n-Propylammonium Perruthenate, a Mild and Convenient Oxidant for Alcohols, Aldrichimica Acta 1990, 23, 13-19. 

Some very mild oxidizing agents are being more and more widely used for the synthesis of very sensitive aldehydes. One of these is known as TPAP (tetra-n-propylammonium perruthen-ate, pronounced tee-pap ). 

Recently two heterogeneous TPAP-catalysts were developed, which could be recycled successfully and displayed no leaching In the first example the tetra-alkylammonium perruthenate was tethered to the internal surface of mesopor-ous silica (MCM-41) and was shown [153] to catalyze the selective aerobic oxidation of primary and secondary allylic and benzylic alcohols. Surprisingly, both cyclohexanol and cyclohexenol were unreactive although these substrates can easily be accommodated in the pores of MCM-41. The second example involves straightforward doping of methyl modified silica, denoted as ormosil, with tetra-propylammonium perruthenate via the sol-gel process [154]. A serious disadvantage of this system is the low-turnover frequency (1.0 and 1.8 h-1) observed for primary aliphatic alcohol and allylic alcohol respectively. 

Ac, acetyl AIBN, azobis(isobutanonitrile) All, allyl AR, aryl Bn, benzyl f-BOC, ferf-butoxycarbonyl Bu, Butyl Bz, benzoyl CAN, ceric ammonium nitrate Cbz, benzyloxycarbonyl m-CPBA, m-chloroperoxybenzoic acid DAST, diethylaminosulfur trifluoride DBU, l,8-diazabicyclo[5.4.0]undec-7-ene DCC, /V. /V - d i eye I oh e x y I c ar bo -diimide DCM, dichloromethyl DCMME, dichloromethyl methyl ether DDQ, 2,3-dichloro-5,6-dicyano-l,4-benzoquinone DEAD, diethyl azodicarboxylate l-(+)-DET, L-(+)-diethyl tartrate l-DIPT, L-diisopropyl tartrate d-DIPT, D-diisopropyl tartrate DMAP, 4-dimethylaminopyridine DME, 1,2-dimethoxyethane DMF, /V./V-dimethylformamide DMP, 2,2-dimethoxypropane Et, ethyl Im, imidazole KHMDS, potassium hexamethyldisilazane Me, methyl Me2SO, dimethyl sulfoxide MOM, methoxymethyl MOMC1, methoxymethyl chloride Ms, methylsulfonyl MS, molecular sieves NBS, N-bromosuccinimide NIS, /V-iodosuccinimide NMO, /V-methylmorpho-line N-oxide PCC, pyridinium chlorochromate Ph, phenyl PMB, / -methoxvbenzyl PPTs, pyridiniump-toluenesulfonate i-Pr, isopropyl Py, pyridine rt, room temperature TBAF, tetrabutylammonium fluoride TBS, ferf-butyl dimethylsilyl TBDMSC1, f-butylchlorodimethylsilane Tf, trifhioromethylsulfonyl Tf20, trifluoromethylsulfonic anhydride TFA, trifluoroacetic acid THF, tetrahydrofuran TMS, trimethylsilyl TPAP, tetra-n-propylammonium perruthenate / -TsOH. / -toluenesulfonic acid... 

Tetra- -propylammonium perruthenate (TPAP, tetrapropyl tetraoxoruthenate) [114615-82-6] M 351.4, m 160 (dec). It is a strong oxidant and may explode on heating. It can be washed with aqueous -propanol, then H2O and dried over KOH in a vacuum. It is stable at room temperature but best stored in a refrigerator. It is soluble in CH2CI2 andMeCN. [Dengelet al. Transition Met Chem 10 98 1985, Griffith et al. J Chem Soc, Chem Commun 1625 1987.]... 

GAC General acid catalysis TPAP Tetra-N-propylammonium perruthenate... 

Some very mild oxidizing agents are being more and more widely used for the synthesis of very sensitive aldehydes. One of these is known as TPAP (tetra-n-propylammonium perruthe-nate, pronounced tee-pap ). TPAP can he used catalytically, avoiding the large amounts of toxic heavy metal by-products generated by most chromium oxidations. The stoichiometric oxidant in this reaction is NMO (JV-methylmorpholine-N-oxide), which is reduced to the amine, reoxidizing the ruthenium to Ru(VII). 

CH3CH2CH2)4N+ RUO4-tetra- -Propylammonium perruthenate (TPAP)... 

A remarkable multicatalytic relay system consisting of tetra-propylammonium perruthenate/N-methylmorpholine iV-oxide (TPAP/NMO) as oxidant, and chiral diarylprolinol trimethylsilyl ethers as organocatalysts, has recently been developed by Rueping et al. and applied in the efficient construction of various valuable chiral molecules through domino reactions. The latter were all based on the in situ generation of ot,p-unsaturated... 

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