Potassium r-butoxide-Dimethyl sulfoxide

Rosenmund reaction Tetramethylthiourea. Lithium diethoxyaluminum hydride. Wolff-Kishner, Huanc-Minlon reduction Hydrazine. Potassium r-butoxide-Dimethyl sulfoxide. Triethanolamine. 

Related Reagents. w-Butyllithium-potassium f-butoxide Potassium Amide Potassium Hexamethyldisilazide Potassium f-butoxide-benzophenone Potassium f-butoxide-r-butyl Alcohol Complex /t-butyllithium-Potassium it t-butoxide Potassium t-butoxide-18-crown-6 Potassium r-butoxide-dimethyl Sulfoxide Potassium f-butoxide-hexamethylphosphoric Triamide Potassium Diisopropylamide Potassium f-heptoxide Potassium Hydroxide Potassium 2-methyl-2-butoxide. 

Isomerizations of Unsaturated Compounds. r-BuOK is an effective base for bringing about migrations of double bonds in alkenes and alkynes via carbanion intermediates, but since the base promotes these reactions most effectively in DMSO, they will be described in more detail under Potassium tert-Butoxide-Dimethyl Sulfoxide. Important exanples of enone deconjugations with i-BuOK/f-BuOH which proceed via di- and trieno-late intermediates are shown in eqs 30 and 31. Potassium i-pentoxide is effective in promoting the latter reaction, but various lithium amide bases are not, apparently because they de-protonate the enone at the a -position regioselectively. The isomerization of Q ,/8-unsaturated imines to alkenyl imines (eq 32) is an important step in an alternative method for reduction-alkylation of a ,/8-unsaturated ketones. ... 

DEHYDROHALOGENATION Amidines, bicyclic. N-Bromosuccinimide. 1,5-Dia-zabicyclo[4.3.01 nonene-5. Diethylamine. Dimethyl sulfoxide. Hexamethylphosphoric triamide. Lithium bromide. Potassium r-butoxide. Sodium amidc-Sodium r-but-oxide. Tetra-n-butylammonium bromide. Triethylamine. 

Gardner and co-workers discovered that halocyclopropanes are dehydrohalo-genated with ease by potassium r-butoxide in dimethyl sulfoxide. With this system the product is generally that formed from the initially produced cyclopropene by migration of the double bond to a position of greater stability outside the three-membered ring. This is followed in some cases by skeletal rearrangement. Examples ... 

Dehydrohalogenation Benzyltrimethylammonium mcsitoate. r-Butylamine. Calcium carbonate. j Uidine. Diazabicyclo[3.4.0]nonene-5. N.N-Dimethylaniline (see also Ethoxy-acetylene, preparation). N,N-Dimelhylformamide. Dimethyl sulfoxide-Potassium r-but-oxide. Dimethyl sulfoxide-Sodium bicarbonate. 2,4-Dinitrophenylhydrazine. Ethoxy-carbonylhydrazine. Ethyldicyclohexylamine. Ethyidiisopropylamine. Ion-exchange resins. Lithium. Lithium carbonate. Lithium carbonate-Lithium bromide. Lithium chloride. Methanolic KOH (see DimethylTormamide). N-PhenylmorphoKne. Potassium amide. Potassium r-butoxide. Pyridine. Quinoline. Rhodium-Alumina. Silver oxide. Sodium acetate-Acetonitrile (see Tetrachlorocyclopentadienone, preparation). Sodium amide. Sodium 2-butylcyclohexoxide. Sodium ethoxide (see l-Ethoxybutene-l-yne-3, preparation). Sodium hydride. Sodium iodide in 1,2-dimethoxyethane (see Tetrachlorocyclopentadienone, alternative preparation) Tetraethylammonium chloride. Tri-n-butylamine. Triethylamine. Tri-methyiamine (see Boron trichloride). Trimethyl phosphite. 

Thermal decomposition. The usual procedure for cari ying out a Wolff-Kishner reduction is to heat a hydrazone with base to a temperature of 200°. Cram e( ai. reported the striking finding that with dimethyl sulfoxide as solvent and potassium r-butoxide as base the reaction can be conducted at room temperature. For example,... 

C-Alkylation Diethyl sulfate. Dimethyl sulfate. Dimethyl sulfoxide reagent (a). Methyl bromide. Methyl chloride. Nitrosonium hexafluorophosphate. Potassium r-butoxide. Sodium amide, Sodium ethoxide. Sodium 2-methyl-2-butoxide. Tetramethylurea. Tri-ethyloxonlum fluuruburate. Trimcthyloxonium fluurubomte. Trimethyloxonium 2,4,6-trlnltrobenzene lulfonale. Triiyliodium. 

Cope ELiMiNATtoN Dimethyl sulfoxide-Potassium r-butoxide. Hydrogen peroxide. See N-Hy-droxyphthalimide. 

Dehydrohalogenation Alumina, see Sulfur tetrafluoride. Alumina-Potassium hydroxide. Cesium fluoride. l,5-Diazabicyclo[4.3.0]nonene-5. l,4-Diazabicyclo[2.2.2]octane. 1,5-Diazabicyclo[5.4.0]undecene-5. Dimethylaminotrimethylstannane. Dimethyl sulfoxide. Hexamethylphosphoric triamide. Lithium chloride. Lithium dicyclohexylamide. Magnesium oxide. Potassium r-butoxide. Potassium fluoride. Potassium triethylmethoxide. Pyridine, see Nitrosyl chloride. Silver fluoride. Silver nitrate. Sodium amide. Sodium bicarbonate, see Nitryl iodide. Sodium isopropoxide. Triethylamine, see Sulfur dioxide. 

Isomerization Aluminum bromide. Boron trifluoride-Hydrogen fluoride. Dimethyl sulfoxide. Formic acid. N-Lithioethylenediamine. Mercuric acetate. Perchloric acid. Potassium r-butoxide. Potassium hydride. Potassium hydroxide. Zinc dust. 

DEHYDROHALOGENATION Dimethyl sulfoxide. Lithium carbonate. Potassium r-butoxide. 

As expected, the hydrogen atoms adjacent to the sulfonyl group of the compound 256 undergo exchange in the presence of potassium r-butoxide and [2H6]dimethyl sulfoxide no selectivity is observed. Deuterium exchange of the vinylic hydrogen atom also occurs, indicating that the vinyl anion... 

The treatment of the 5-amino-trioxane (76) with potassium r-butoxide in dimethyl sulfoxide gives the amide (78) with light emission (Scheme 8) <76TL4627>. Deprotonation of the amine initiates the reaction thereby eliminating isopropanal and producing the dioxetane (77). Scission of the latter produces (78), acetone, and light. 

The cation of the metal /m.-butoxide strongly influences the rates but not the products of alkene isomerizations. For isomerization of 1-butene in dimethyl sulfoxide solutions at 55°C, the relative catalytic effectiveness of alkali / r/,-butoxides increase in the order NaOBu 1.0 KOBu 116 CsOBu 284, RbOBu, 447. This is probably attributable to the fact that large cations are more weakly bonded to the alkoxide ion than smaller cations . The anion of the alkoxide also strongly influences its catalytic effectiveness. Potassium tert.-buioxide is 126 times as effective a catalyst for 1-butene isomerization as potassium methoxide in dimethyl sulfoxide at 55°C . The rate of potassium / r/.-butoxide-catalyzed 1-butene isomerization in DMSO is strongly retarded by addition of / r/.-butyl alcohol to the solvent, probably due to hydrogen bonding between the alkoxide and the alcohoP . 

Although not electrophile-driven, it should be borne in mind that base-induced cyclizations of homopropargylic alcohols are useful methods. Thus, exposure of alcohol 261 to potassium r-butoxide in dimethyl sulfoxide delivers an excellent yield of the dihydrofuran 262 <89CC1371>. In much the same way, ort/to-alkynyl anilines 263 can be converted into 2-substituted indoles 264 <00AG(E)2488>. 

Double dehydrohalogenation to form terminal alkynes may also be carried out by heating geminal and vicinal dihalides with potassium r butoxide in dimethyl sulfoxide. 

The benzyl group can serve as an alcohol-protecting group when acidic conditions for ether cleavage cannot be tolerated. The benzyl C-O bond is cleaved by catalytic hydrogenolysis," or with sodium in liquid ammonia. Allyl ethers are an alternative to benzyl ethers as a protecting group. Allyl ethers may be isomerized quantitatively by potassium r-butoxide in dimethyl sulfoxide to propenyl ethers, which are quite labile to dilute acid. ... 

R. The use of butyllithium in tetrahydrofuran or ether-hexane affords the triene 1n only 50-60% yield. When the ylide was generated with sodium hydride or potassium tert-butoxide in dimethyl sulfoxide by the submitter, the Wittig reaction gave triene containing 10-20% of the Z isomer. Part C illustrates the selective hydroboration of a diene with disiamylborane.1 The reaction is best carried out by adding preformed disiamylborane to the triene. Lower yields of homogeraniol were obtained by the submitter when the triene was added to the borane reagent. 

The carbinol 19 (R = H) was obtained from a reduction of ketone 18 with borohydride (Scheme 2). Compound 19 was then dehydrated with p-toluenesulfonic acid to give the 5H-azaazulenone 20, whose structure was proved by NMR spectroscopy. A mixture of approximately equal amounts of 21 and 21a was formed by acid-catalyzed dehydration of 19 (R = CH3) Wittig olefination of 18 gave the exomethylene derivative 21, which on isomerization with potassium t-butoxide in dimethyl sulfoxide (DMSO) gave a mixture of 60% 21 and 40% 21a. Surprisingly, no isomers of type 17b/c were observed (82JCS(P1)1123). 

The dehydrohalogenation of alkyl halides is usually carried out with sodium methoxide in methanol, sodium ethoxide in ethanol, or potassium ferr-butoxide in either r t-butyl alcohol or dimethyl sulfoxide, (CH3) S0. 

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