Potassium permanganate alkynes with

Treating alkynes with ozone or with basic potassium permanganate leads to... 

N-Substituted amides derived from 2-chloro- or4-chloronicotinic acid react with CH-acidic nitriles in the presence of base to yield amino derivatives of [l,6]naphthytid-5(6//)-ones and [2,7]naphthyrid-l(2//)-ones <1997JHC397>. 3-(l-Alkylamino)pyridines react with electron-deficient alkynes (acetylene dicatboxylates) in the presence of acid to give l,2-dihydro[2,7]naphthyridine-3,4-dicarboxylates in up to 72% yield compounds unsubstituted at C-1 were readily oxidized with potassium permanganate to naphthyridine-l-ones <2005TL3953>. 

A very efficient, stereospecific synthesis of DL-ribose was based26 on the use of l,l-diethoxy-5-(tetrahydropyran-2-yloxy)-2-pentyn-3-ol as the substrate. Catalytic hydrogenation of this alkyne to the cts-alkene was accompanied by cyclization, to give 2-ethoxy-2,5-dihydro-5-(tetra-hydropyran-2-yloxy)furan (35). cis-Hydroxylation of the double bond in 35 was effected with potassium permanganate, yielding the ethyl DL-ribofuranoside derivative 36, which was hydrolyzed to DL-ribose. 

Reaction of an alkene with hot basic potassium permanganate (KMn04) results in cleavage of the double bond, and formation of highly oxidized carbons. Therefore, unsubstituted carbon atoms become CO2, mono-substituted carbon atoms become carboxylates, and di-substituted carbon atoms become ketones. This can be used as a chemical test (known as the Baeyer test) for alkenes and alkynes, in which the purple colour of the KMn04 disappears, and a brown Mn02 residue is formed. 

Finally, [Method (c)], treatment of an internal alkyne with potassium permanganate under PTC conditions leads to a good yield of a 1,2-diketone.146 The reaction probably proceeds via hydroxylation of the triple bond, tautomeric rearrangement to the a-ketol, and oxidation to the diketone. The reaction is illustrated by the conversion of 1-phenylpent-l-yne to l-phenylpentane-1,2-dione (Expt 5.101). 

Various cyclopropenone derivatives react with peracids to yield the corresponding alkynes as primary products. However, the alkynes are themselves oxidized under the reaction conditions and the reaction is impractical as an alkyne synthesis. Two possible modes of alkyne formation are depicted in equation 97" ". Reaction of diphenylcyclopropenone with singlet oxygen or potassium permanganate gives" " desoxybenzoin. 

SoHd-liguid phase-transfer catalysis. Crown ethers have commonly been used as catalysts for reactions between a solid-liquid interface, and quaternary ammonium and phosphonium salts have been used only as catalysts for reactions in two-phase liquid liquid reactions. However, several laboratories have reported that the latter catalysts are also satisfactory for two-phase solid liquid reactions. Thus dichlorocarbene can be generated from chloroform and solid sodium hydroxide under catalysis from benzyltriethylammonium chloride in yields comparable to those of the classical Makosza method. Another example of this type of catalysis is the oxidation of terminal and internal alkynes by solid potassium permanganate in CH2CI2 with Adogen 464 as catalyst. Aliquat 336 has been found to be as satisfactory as a crown ether for certain displacement reactions with NaOAc, KSCN, KNOa, and KF in CH3CN or CHaCla. ... 

Treating alkynes with ozone followed by acetic acid, or with basic potassium permanganate followed by acid, leads to cleavage at the carbon—carbon triple bond. The products... 

Despite its molecular formula, benzene for the most part does not behave as if it were unsaturated. For instance, it does not decolorize bromine solutions the way alk-enes and alkynes do (Sec. 3.7a), nor is it easily oxidized by potassium permanganate (Sec. 3.17a). It does not undergo the typical addition reactions of alkenes or alkynes. Instead, benzene reacts mainly by substitution. For example, when treated with bromine (Br2) in the presence of ferric bromide as a catalyst, benzene gives bromobenzene and hydrogen bromide as products. 

Hydroboration of alkynes leads to an enol after treatment with NaOH/HgOg, and tautomerization gives an aldehyde from terminal alkynes, or a ketone from internal alkynes 44, 78, 83. Dilute potassium permanganate and osmium tetroxide react with alkenes to give a manganate ester or an osmate ester, respectively. Both of these products are decomposed under the reaction conditions to give a vicinal (l,2)-cis-diol 49, 50, 83, 96. 

Two common types of unsaturated compounds are alkenes and alkynes, characterized by the carbon-carbon double and triple bonds, respectively, as the functional group. The two common qualitative tests for unsaturation are the reaction of the compounds with bromine in dichloromethane and with potassium permanganate. In both cases, a positive test is denoted by decoloration of the reagent. There are no simple, direct ways to prepare solid derivatives of unsaturated aliphatic compounds having no other functional groups. 

Bromine adds to the carbon-carbon double bond of alkenes to produce dibro-moalkanes (Eq. 25.25) and reacts with alkynes to produce tetrabromoalkanes (Eq. 25.26). When this reaction occurs, molecular bromine is rapidly consumed, and its characteristic dark red-orange color disappears if bromine is not added in excess. The nearly instantaneous disappearance of the bromine color is a positive test for unsaturation. The test is ambiguous, however, because some alkenes do not react with bromine, and some react very slowly. In the case of a negative test, the Baeyer procedure using potassium permanganate (Sec. 25.8B) should be performed. 

Cyclic diketones can be the predecessors of quinoxaline macrocycles, obtained in one stage with the oxidation of cyclic alkenes with potassium permanganate (1971JA3303) or in two stages by the cyclotrimerization of cyclic alkynes and subsequent ozonolysis of compounds 18 (1986JOC3257). Along with the formation of diketone 4 the latter reaaion leads, to the unstable hexaketone 19. The reaction of the mixture of compounds 4 and 19 with the DAB leads to macrocycles 20 and 21 with one or three quinoxaline fr pients, respectively, with 10% and 3% yields, calculated in two st es.The synthesis of the macrocycle 20a from the analytically pure diketone 4a was in quantitative yield. 

The oxidation of alkynes to a-diketones with potassium permanganate is a well-known reaction, but the early examples gave carboxylate salts that are soluble in aqueous permanganate. What conditions would you choose to oxidize 1-phenyl-1-pentyne to 1-phenyl-1, 2-pentanedione [86]... 

Oxidations of alcohols on solid potassium or sodium permanganate surfaces take place under mild conditions with high yield and easy workup. Solid sodium permanganate can also oxidize aldehydes and sulfides but not alkenes or alkynes the solid reagent is thus more selective than the oxidant in solution. Mechanistic aspects (including an observed need for trace quantities of water at the crystal surface,... 

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