Alcohols TPAP tetrapropylammonium

Practical Cr -catalyzed oxidations of alcohols have not been adopted widely, but Pr4N+ Ru04 (TPAP, tetrapropylammonium perruthenate) catalyzes the oxidation of alcohols to aldehydes by a stoichiometric oxidant such as NMO, H2O2, or O2 itself. The Ru(VII) complex oxidizes alcohols by the same mechanism described earlier for stoichiometric Cr species. The stoichiometric oxidant then reoxidizes the Ru(V) by-product back to Ru(VII). 

Finally, single bead FT-IR has been further exploited in many applications, such as the study of the tetrapropylammonium perrutherate (TPAP)-catalyzed oxidation of supported alcohols [167], the ring opening of a supported oxazolidinone [173], and the solid-phase synthesis of a benzimidazole [174]. 

Hydroboration occurred from the less hindered top face of rac-29 and resulted in the formation of alcohol rac-30. After a three-step sequence which included oxidation with tetrapropylammonium perruthenate (TPAP), methyl lithium addition and repeated oxidation with TPAP, ketone rac-31 was isolated. Finally, epimerization of the stereogenic center at C-7 to the correct configuration and methylenation with the Lombardo reagent led to the formation of racemic kelsoene (rac-1). 

Fig. 14.14. TPAP oxidation of an alcohol to an aldehyde TPAP stands for tetrapropylammonium perruthenate.

The following Swern oxidation is an inexpensive, mild and fast transformation. It provides aldehydes starting from primary alcohols in the absence of water, exclusively. Other mild oxidation methods for the formation of aldehydes are known Dess-Martin periodinane (DMP), o-iodoxybenzoic acid (IBX), chromium(III) reagents, tetramethylpiperidine 7V-oxide and sodium hypochlorite (TEMPO/NaOCl), tetrapropylammonium perruthenate and N-methylmorpholine 7V-oxide (TPAP/NMO), " and palladium(II)-catalyzed oxidations are reported. ... 

Griffith, W. P., Ley, S. V., Whitcombe, G. P., White, A. D. Preparation and use of tetrabutylammonium perruthenate (TBAP reagent) and tetrapropylammonium perruthenate (TPAP reagent) as new catalytic oxidants for alcohols. J. Chem. Soc., Chem. Common. 1987,1625-1627. 

F.i. Tetrapropylammonium Perruthenate-Ley Oxidation. Ruthenium derivatives have been used for oxidation reactions. A particularly useful one is TPAP, introduced by Ley for the oxidation of alcohols and called Ley oxidation. 1 2 a very mild oxidizing agent that is compatible with many sensitive... 

As a further extension, the Kim group very recently developed the aerobic oxidation and [l,5]-hydride transfer/cyclization sequence starting from readily available ortho tertiary amine substituted cinnamyl alcohols 24 (Scheme 4.12). The tetrapropylammonium perruthenate (TPAP) was identified as the competent catalyst for the initial aerobic oxidation of the allylic alcohols. The synthetically useful tetrahydroquinoline derivatives 25 were prepared in moderate yields and high level of enantioselectivity. 

A series of homo-allylic steroidic alcohols were oxidized with N-methyl morpholine N-oxide (NMO) in the presence of tetrapropylammonium perrhutenate (TPAP) (Eq. 70, see Ch. 9, p. 358).The mechanism probably implies the preliminary oxidation of the alcohol. A labile silyl enol ether is preserved under the conditions specified. 

The oxidation of alcohols with (l,l-dimethylethyl)benzene-sulfenamide is extremely mild and many sensitive functional groups such as epoxides and alkenes are tolerated hy the reaction conditions (eq 5). In the case of alcohol 1, oxidation with tetrapropylammonium perruthenate (TPAP) resulted in only 58% yield and Swern oxidation was unsuccessful. Epimerizable aldehydes such as the protected phenylglycinol 2 do not undergo racemization when oxidized (eq 6). ... 

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