Potassium tert-butoxide/dimethyl sulfoxid

Various alkylcyclopropanes have been converted to (l-alkenyl)cyclopropanes by dehydrogenation with trimethylsilyl triflate, selenium dioxide,tetrachloro-1,4-benzoquinone, 2,3-dichloro-5,6-dicyano-l,4-benzoquinone, di-/er/-butyl dicarbonate and potassium tert-butoxide/dimethyl sulfoxide. A related transformation is the Ramberg-Back-lund reaction of bis(l-trimethylsilylcyclopropylmethyl) sulfone which gave ( )-l,2-bis(l-trimethylsilylcyclopropyl)ethene in fair yield. ... 

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. ... 

Potassium tert-butoxide dimethyl sulfoxide Exo- from endo-cyclic carbon-carbon double bonds... 

Potassium tert-butoxide dimethyl sulfoxide Cyclopropanes... 

Potassium tert-butoxide/dimethyl sulfoxide 9-Thiabicyclo[4.2 l]nona-2,4,7-triene 9,9-dioxide ring by bishomoconjugative Ramberg-Baddund rearrangement... 

Potassium tert-butoxide/dimethyl sulfoxide Carboxylic acids from hindered carboxylie acid esters... 

Potassium tert-butoxide/dimethyl sulfoxide 0-Propenyl from 0-allyl derivatives Allyl as protective group... 

Potassium tert-butoxide/dimethyl sulfoxide Ring closure with aldehydes 2,3-Dihydro-lH-3-benzazepines... 

Potassium tert-butoxide dimethyl sulfoxide Ethylene derivatives from sulfoxides and sulfones 1,3-Dienes from cyclic sulfoxides... 

Similarly sodium methoxide (NaOCHj) is a suitable base and is used m methyl alco hoi Potassium hydroxide m ethyl alcohol is another base-solvent combination often employed m the dehydrohalogenation of alkyl halides Potassium tert butoxide [K0C(CH3)3] is the preferred base when the alkyl halide is primary it is used m either tert butyl alcohol or dimethyl sulfoxide as solvent... 

Compound A (C4H10) gives two different monochlondes on photochemical chlorination Treatment of either of these monochlondes with potassium tert butoxide in dimethyl sulfoxide gives the same alkene B (CaHg) as the only product What are the structures of compound A the two monochlondes and alkene B2... 

Compounds A and B are isomers of molecular formula C9Hi9Br Both yield the same alkene C as the exclusive product of elimination on being treated with potassium tert butoxide in dimethyl sulfoxide Hydrogenation of alkene C gives 2 3 3 4 tetramethylpentane What are the structures of compounds A and B and alkene C2... 

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

Potassium tert butoxide reacts with halobenzenes on heating in dimethyl sulfoxide to give ten butyl phenyl ether... 

The classical procedure for the Wolff-Kishner reduction—i.e. the decomposition of the hydrazone in an autoclave at 200 °C— has been replaced almost completely by the modified procedure after Huang-Minion The isolation of the intermediate is not necessary with this variant instead the aldehyde or ketone is heated with excess hydrazine hydrate in diethyleneglycol as solvent and in the presence of alkali hydroxide for several hours under reflux. A further improvement of the reaction conditions is the use of potassium tert-butoxide as base and dimethyl sulfoxide (DMSO) as solvent the reaction can then proceed already at room temperature. ... 

Equilibration of the alkyne 85 with potassium hydroxide alone produced a 1 1 mixture of allene 86 and starting material complete conversion to 86 resulted from treatment with potassium hydroxide or potassium tert-butoxide in dimethyl sulfoxide. ... 

Figure 7. First derivative ESR spectra of radical anions observed in dimethyl sulfoxide solutions of potassium tert-butoxide. Top, autoxidation product of diphenylamine. No signal was observed in the absence of oxygen. Middle, autoxidation of 4-hydroxy-diphenylamine. Bottom, spontaneous reduction product of mono-anil of p-benzoquinone.

The isomerization of allyl ethers to 1-propenyl ethers, which is usually performed with potassium tert-butoxide in dimethyl sulfoxide, can also be carried out under milder conditions using tris(triphen-ylphosphine)rhodium chloride,208 and by an ene reaction with diethyl azodicarboxylate,209,210 which affords a vinyl ether adduct. Removal of an O-allyl group may be achieved by oxidation with selenium dioxide in acetic acid,211 and by treatment with N-bromosuccinimide, followed by an aqueous base.201,212... 

Potassium tert-butoxide was obtained from the Aldrich Chemical Company, Inc. The dimethyl sulfoxide was distilled from calcium hydride and stored under argon. 

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 discovery that sodium in the presence of small amounts of organosodium compounds, produced in situ or deposited on alumina, acts as an effective catal for double bond isomerization of alkenes and cyclenes U) triggered much research in this field (2). It was subsequently discovered that base-catalyzed isomerization of olefins may proceed in homogeneous solutions using lithium ethylenediamine (3) or potassium tert-butoxide (UBuOK) in dimethyl sulfoxide (DMSO) (4). 

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