Alkylations potassium ferf-butoxide

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

If, however, the base itself is a crowded one, such as potassium ferf-butoxide, even primary alkyl halides undergo elimination rather than substitution ... 

Exercise 8-26 a. Why is potassium ferf-butoxide, KOC(CH3)3, an excellent base for promoting elimination reactions of alkyl halides, whereas ethylamine, CH3CH2NH2, is relatively poor for the same purpose ... 

The application of strong bases to hydrocarbons which contain a sp3 hybridized carbon and a conjugated system may abstract a proton and form a fully conjugated carbanion. This reaction has several synonyms such as deprotonation, proton abstraction or metalation reactions. The most common bases are alkyl lithium derivatives, e.g., butyl lithium21 24). Sometimes the addition of tetramethylethylenediamine (TMEDA) or potassium ferf-butoxide is required especially when dianions and polyanions are prepared 24e,f). Ether solvents or hydrocarbon solvents are most common. This process can be demonstrated by the preparation of anthraene dianion 22 from 9,10-dihydroanthracene (1)25). The metalation reaction can also be carried out in the NMR tube. 

Alkylpyrido[2,3-d]pyridazin-5(6//)-one and 5-alkylpyrido[2,3-t/]pyridazin-8(7//)-one, converted into their anions by potassium ferf-butoxide or sodium hydride in dimethylfor-mamide, are, V-alkylated at position 6 or 7 respectively by alkyl or arylalkyl halides, 9 90 e.g. formation of 8 or 9.90... 

METHYL HYDRATE (67-56-1) CH O CH3OH Flammable liquid. Forms explosive mixture with air [explosion limits in air (vol %) 6.0 to 36.5 flash point 52 F/11 C autoignition temp 725°F/385°C 867°F/464°C " Fire Rating 3]. Violent reaction (possible fire and/or explosion) with strong oxidizers strong mineral acids (e.g., nitric, sulfuric, perchloric) acetyl bromide alkyl aluminum salts beryllium dihydride bromine, chromic acid l-chloro-3,3-difluoro-2-methoxycyclopropene, cyanuric chloride diethylzinc, isophthaloyl chloride potassium-ferf-butoxide phosphorus trioxide platinum-black catalyst (ignition) potassium sulfur diimide Raney-nickel catalysts 2,4,6-trichlorotriazine, triethylaluminum, 1,3,3 -trifluor o-2 -... 

Write structural formulas for all the products that would be obtained when each of the following alkyl halides is heated with potassium ferf-butoxide in terf-butyl alcohol. When more than one product results, you should indicate which would be the major product and which would be the minor product(s). You may neglect cis-trans isomerism of the products when answering this question. 

The regioselectivity (a vs. y) is controlledby many factors, such as the nature of the heteroatom, the base, the substituents bonded to the heteroatom, the electrophile, the solvent, and the reaction conditions. It has been proposed, as a rule of thumb, that for a given counter ion, e.g., lithium, anion-destabilizing substituents (e.g., OR, NR2) favor the attack by alkyl halides and protons at the y-position, while carbonyl compounds undergo reaction preferentially at the a-position. The complementary regioselectivity is encountered when anion-stabilizing substituents (e.g., SR, BR2) are bonded to the allyl moiety. A list of n-butyllithium/potassium ferf-butoxide metalated heterosubstituted alkenes is shown in Table 3. 

Chiral (5)-2-(methoxymethyl)-l -[( )-3-phenyl-2-propenyl]pyrrolidine obtained from (S)-2-(meth-oxymethyl)pyrrolidine26,30 and ( )-3-bromo-1-phenyl-1-propene, is deprotonated by potassium rert-butoxide/ferf-butyllithium27-28 generating the chiral allyl carbanion, the alkylation of which affords the enamines, which can be hydrolyzed to give 3-alkylated 3-phenylpropanals. 

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