Potassium solid-supported

J. Tercio, B.Ferreira, W. O. Cruz, P. C. Vieira, andM. Yonashiro, Carbon-carbon double bond cleavage using solid-supported potassium permanaganate on silica gel, J. Org. Chem., 52 (1987) 3698-3699. 

Olefinations using a solid-supported triphenylphosphine were accomplished within 5 min of microwave heating at 150 °C using potassium carbonate as the base and methanol as the solvent (Scheme 7.96). A variety of aldehydes and organic halides were studied with the solid-supported phosphine, yielding the corresponding alkenes in excellent purities. 

Primary and secondary alcohols are oxidized slowly at low temperatures by benzyltriethylammonium permanganate in dichloromethane primary alcohols produce methylene esters (60-70%), resulting from reaction of the initially formed carboxylate anion with the solvent, with minor amounts of the chloromethyl esters and the carboxylic acids. Secondary alcohols are oxidized (75-95%) to ketones [34] the yields compare favourably with those obtained using potassium permanganate on a solid support. 1,5-Diols are oxidized by potassium permanganate under phase-transfer catalytic conditions to yield 8,8-disubstituted-8-valerolactones [35] (Scheme 10.1). 

In view of the multicomponent nature of the tandem [4 + 2] / [3 + 2] cycloaddition, the potential for a combinatorial approach to the synthesis of nitroso acetals has been investigated on solid-phase supports. The incorporation of either the dipolarophile or the starting nitroalkene on a Wang-type resin is compatible with the tandem cycloaddition promoted at high pressures (Schemes 2.28 and 2.29). The solid-supported nitroso acetals are subsequently liberated (in moderate yields from the staring nitroalkene) upon the addition of a catalytic amount of potassium cyanide in triethylamine and methanol or by reduction with lithium aluminum hydride (LAH) (261,264). 

For the direct use of tyrosine 0-sulfate in peptide synthesis a set of -protected Tyr(S03H) derivatives were synthesized that can be combined with the most common protection schemes. In addition to Z-Tyr(S03Ba1/2)-0Ba1/2 (11)[3S1 (see Section 6.6.1.1.4), the related Boc and Fmoc derivatives have been synthesised as barium, sodium, potassium salts, and even as tetrabutylammonium salts due to their better solubility in solvents generally used for automated synthesis on solid supports.1152 154 155 ... 

Lately, a number of papers have dealt with microwave-assisted reactions on palladium-doped A1203. Villemin reported on Stifle, Suzuki, Heck and Trost—Tsuji reactions where potassium fluoride on alumina was used as the base26. The reactions were carried out without solvent or stabilising phosphine ligands in single-mode reactors. The Stifle reactions were noteworthy as the toxic organotin residue remained adsorbed on the solid support, thus allowing a simplified work-up procedure for the otherwise unpleasant, and toxic, stannous by-products. Both the Stifle and the Suzuki reactions could be performed under air. Furthermore, it was noted that with experiments where the... 

Trans -substituted diarylalkenes undergo oxidative cleavage upon treatment by potassium permanganate in the presence of moist alumina as a solid support (equation 32)158. Under the same conditions, cyclic alkenes, with medium-sized rings, give acyclic dialdehydes (equation 33). 

An aldehyde was mixed with solid supported triphenylphosphine oxide (3 equiv.), alkyl halide (4 equiv.), and potassium carbonate (4 equiv.) in methanol (2 ml). The mixture was heated at 150° for 5 min. The residue was filtered through a short plug of silica gel and washed. The solution was concentrated and purified by reverse-phase high-performance liquid chromatography (RP-HPLC). 

Rostamizadeh et al. [19] found potassium fluoride to be an efihcient catalyst and solid support for the one-pot solvent-free synthesis of 3,5-disubstituted-l,2,4-oxadiazoles. 

Rostamizadeh S, Ghaieni HR et al (2010) Clean one-pot synthesis of 1,2,4-oxadiazoles under solvent-free conditions using microwave irradiation and potassium fluoride as catalyst and solid support. Tetrahedron 66 494-497... 

The ester function is in general unaffected by most of the Nef reaction conditions. Of particular interest are those reactions using methanol or ethanol as the solvent for hydrolysis." " It is worth noting that treatment of a nitronate salt by sulfuric acid in absolute methanol at -10 °C yields dimethyl acetal, i.e. a protected form of the aldehyde. For solid phase hydrolysis, silica gel" " or potassium permanganate supported on silica gel " are remarkably efficient reagents, especially for small scale reactions. 

Potassium permanganate. 13, 258-259 14, 267 15,273-274 18,301 19,277-278 Oxidations. Well-known oxidation processes have been modified by ultrasound assistance, dispersion of KlVInO on solid supports such as alumina, " zeolite, and kieselguhr. ... 

A number of different stationary phases have been used, mostly on a solid support impregnated with potassium hydroxide from very polar ones, such as polyglycols, to non-polar ones, such as silicone rubber. Packed columns have mostly been used, but good separations have also been achieved with capillary columns. 

A good separation was obtained on a packed column of 30 % polyethylene glycol 4000 on silica gel impregnated with 20 % potassium hydroxide. Potassium hydroxide was used to reduce adsorption to the solid support. The results are given in Table 6.1. 

In a related transformation, cyclopropanes 7 were obtained from active methylene compounds and electron-deficient alkenes by the action of iodine and potassium fluoride supported on solid alumina. 

The synthesis of a Boc-hke linker oufhned in Scheme 8 was performed in a straightforward maimer. Commercially available 3-methyl-l,3-hutanediol 17 was reacted with one equivalent of potassium tcrt-butoxide, and the resulting monoalkoxide was coupled to a chloromethyl support to create the solid support-bound tertalkyl alcohol 18, which was activated with CDI. In order to enhance the acylating reaction, the imidazole intermediate was methylated before the addition of the amine, leading ultimately to 19. The amine 20 was released by exposure to 10% TFA. 

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