Potassium-f-butoxide

Chloroethylamino)isothiazoIe (111) cyclizes to 3-aziridinylisothiazoIe (112) under the influence of potassium f-butoxide, but undergoes intramolecular quaternization if kept at 50 °C for two days, to give compound (113 Scheme 14) (79JOC1118). 

Cleavage of N—N by potassium f-butoxide to give amidine (164) was observed with diaziridine (134). This is the only known analog of the generally observed acid amide formation from oxaziridines (74JPR999). 

In Cram s first synthesis of a chiral bis-binaphthyl system, optically pure binaph-thol and diethylene glycol ditosylate were heated at reflux in tetrahydrofuran solution for 15 h with potassium f-butoxide, two products were obtained. The 1 + 1 product (mp 230—231°) was isolated in 5% and the 2 + 2 product (mp 123—126°) was obtained in 31% yield. The reaction is shown in Eq. (3.51). 

When phenolic nucleophiles were used, either potassium hydroxide or potassium f-butoxide was generally chosen as the base. When aliphatic hydroxyls constituted the nucleophiles, a stronger base was required and sodium hydride was generally chosen. 

Further functionalization has been carried out in the mixed benzo-binaphtho crown shown in Eq. (3.55). Using 2-allylcatechol as starting material, the mixed crown was prepared in the usual fashion. The allyl group was isomerized to a propenyl substituent by treatment with potassium f-butoxide in a benzene/f-butanol mixture. Selective ozono-lysis affords the aldehyde. 

This procedure has been patterned after the method by which the carbethoxy group is introduced into a few alicyclic ketones 6 and several cyclic ketones. Cyclohexanone has been reported to yield 50% of 2-carbethoxycyclohexanone when treated with sodium hydride and diethyl carbonate using ether as the solvent.7 The preparation of 2-carbethoxycycloheptanone using potassium f-butoxide and diethyl carbonate in benzene has been reported in 40% yield.8 Jacob and Dev report an 80% yield of the latter compound using sodium hydride as the base.9... 

Bromoacetyl fluoride, 46, 6 Bromobenzene, reaction with potassium f-butoxide, 46, 89... 

The polymerization of l,4-bis(halomethyl)benzenes to PPVs in the presence of a large excess of potassium f-butoxide is referred as the Gilch route [81]. The method was first described for the synthesis of unsubstituted PPV 60, but -unfortunately - this route produces the PPV as an intractable, insoluble powder. However, the adaptation of the Gilch route to the polymerization of l,4-bis(halo-methyl)benzenes possessing solubilizing side groups gives access to soluble PPV materials. 

Significantly, (a) a-sulfonyl carbanions of thiirane dioxides, generated from the latter in the presence of strong bases such as potassium f-butoxide and alkoxide ions , do epimerize to relieve steric repulsion between substituents as in 42 above and (b) the a-hydrogen in aryl-substituted three-membered sulfoxides (e.g. 46c) are sufficiently acidic to... 

The key cyclization in Step B-2 was followed by a sequence of steps that effected a ring expansion via a carbene addition and cyclopropyl halide solvolysis. The products of Steps E and F are interesting in that the tricyclic structures are largely converted to tetracyclic derivatives by intramolecular aldol reactions. The extraneous bond was broken in Step G. First a diol was formed by NaBH4 reduction and this was converted via the lithium alkoxide to a monomesylate. The resulting (3-hydroxy mesylate is capable of a concerted fragmentation, which occurred on treatment with potassium f-butoxide. 

C. 2-Methylmercapto-N-methyl-A 2-pyrroline. 2-MethyImer-capto-N-methyl-A -pyrrolinium iodide (662 g., 2.57 moles) is suspended in 1.25 1. of anhydrous ether in a 4-1. three-necked flask equipped with a mechanical stirrer and a reflux condenser with a segment-shaped paddle. Potassium f-butoxide (448 g., 4.0 moles) is added in one batch to this suspension with vigorous stirring. The mixture warms up a little, and later the solid becomes fine-grained and more mobile as a result of separation of potassium iodide. After being stirred for 1.5 hours at room temperature, the mixture is treated with 1.81. of anhydrous ether and boiled under reflux on a water bath for 5 hours. 

The yield of 11,ll-dichlorotricyclo[4.4.1.01,6]undeca-3,8-diene strongly depends on the quality of the potassium <-butoxide used. Commercially available, sublimed potassium i-butoxide was employed. When freshly sublimed potassium f-butoxide is utilized, yields of up to 45% of 11,ll-dichlorotricyclo[4.4.1.01- ]undeca-3,8-diene can be obtained. Potassium <-butoxide, prepared by the method of Doering, gave yields comparable to those achieved with the commercial product. 

Mildly basic liquiddiquid conditions with a stoichiometric amount of catalyst prevent hydrolysis during alkylation [101] and, more recently, it has been established that solid-liquid or microwave promoted reactions of dry materials are more effective for monoalkylation [102-106] of the esters and also permits dialkylation without hydrolysis. Soliddiquid phase-transfer catalytic conditions using potassium f-butoxide have been used successfully for the C-alkylation of diethyl acetamido-malonate and provides a convenient route to a-amino acids [105, 107] use of potassium hydroxide results in the trans-esterification of the malonate, resulting from hydrolysis followed by O-alkylation. The rate of C-alkylation of malonic esters under soliddiquid phase-transfer catalytic conditions may be enhanced by the addition of 18-crown-6 to the system. The overall rate is greater than the sum of the individual rates observed for the ammonium salt or the crown ether [108]. 

Cyclic ketene acetals, which have utility as co-polymers with functional groups capable of cross-linking, etc., have been prepared by the elimination of HX from 2-halomethyl-l,3-dioxolanes. Milder conditions are used under phase-transfer conditions, compared with traditional procedures, which require a strong base and high temperatures. Solid liquid elimination reactions frequently use potassium f-butoxide [27], but acceptable yields have been achieved with potassium hydroxide and without loss of any chiral centres. The added dimension of sonication reduces reaction times and improves the yields [28, 29]. Microwave irradiation has also been used in the synthesis of methyleneacetals and dithioacetals [30] and yields are superior to those obtained with sonofication. 

The regio- and diastereo-selectivity of the Michael addition of 2-phenylcyclo-hexanone with a,p-unsaturated ketones are dependent on the reaction conditions. Mixtures of all six diastereoisomers resulting from reaction at either the 2- or 6-position of the cyclohexanone ring can be obtained using solid potassium hydroxide with tetra-n-butylammonium or A-benzylephcdrinium bromide catalysts. At 20°C with tetra-n-butylammonium bromide, the ratio of the 2,2- and 2,6-disubstituted cyclohexanones is ca. 3 2, but at higher temperatures with solid potassium f-butoxide the kinetically formed 2,6-isomer predominates (ca. 5 1) with the (2S,6R, R )-stereoisomer dominant, whereas greater amounts of the thermodynamically preferred 2,2-(2S,lR )-isomer are obtained with the chiral catalyst [61]. 

The submitters have also used commercially available dry potassium f-butoxide with varying success in this reaction with a sample purchased from M.S.A. Research Corporation a 65% yield of product was obtained. The submitters reported a 65-76% yield range for this step. 

Potassium f-butoxide may be obtained from MSA Research Corporation, Callery, Pennsylvania. 

General procedure To a flame-dried, three-necked, 250 mL, round-bottomed flask equipped with argon inlet, addition funnel and gas bubbler was added 100 mL of dry 1,2-dimethoxyethane (DME) with 0.20 g (0.98 mmol) of triflate [R, R =Me] and 0.50 g (1.2 mmol) of diphenyl diteUuride. The reaction mixture was cooled to 50°C and a solution of potassium f-butoxide (0.15 g, 1.3 mmol) in 50 mL of dry DME was added dropwise. After the addition, stirring was continued for 15 min at -50°C, then the reaction was aUowed to warm to room temperature. DME was then removed on a rotary evaporator and the residue taken up in hexane and filtered. The resulting coloured solution was chromatographed on activated silica (hexane as eluent). Isolated yield was 0.12 g (26%), as an orange oil. 

Dibutyltelluronium benzylide, generated by treatment of the telluronium salt with potassium f-butoxide, behaves similarly to the above-stabihzed ylides, undergoing Wittig-type olefmations with aromatic aldehydes. 

Bromo- and iodocyclopropanes cannot be prepared by the direct halogenation of cyclopropanes. Substituted chloro- and bromocyclopropanes have been synthesized by the photochemical decomposition of a-halodiazomethanes in the presence of olefins iodocyclopropanes have been prepared from the reaction of an olefin, iodoform and potassium f-butoxide followed by the reduction of diiodocyclopropane formed with tri-w-butyl tin hydride. The method described employs a readily available light source and common laboratory equipment, and is relatively safe to carry out. The method is adaptable for the preparation of bromo- and chlorocyclopropanes as well by using bromodiiodomethane or chlorodiiodomethane instead of iodoform. If the olefin used will give two isomeric halocyclopropanes, the isomers are usually separable by chromatography. ... 

Potassium amide, 52, 75 Potassium azide, 50,10 Potassium f-butoxide, 52,53 Potassium hydroxide complex with dicyclohexyl-18-crown-6 polyether, 52,77... 

A stereochemical behavior similar to that of the 1-bromo-l-lithio aUcene 164 with regard to chiral aldehydes is shown by the hthiated methoxyallene 183. When added to iV,iV-dibenzylated a-aminoaldehydes 188, it reacts with non-chelate control so that awh -carbinols 189 are obtained predominantly. Diastereomeric ratios of 189 190 range from 80 20 to 95 5. As outlined above, the hydroxyalkylated allenes 189/190 can be converted into furanones 191/192 upon treatment with potassium f-butoxide and subsequent acid hydrolysis" . When, on the other hand, the adducts of 183 to the aldehydes 193 are submitted to an ozonolysis, A-protected a-hydroxy-/3-amino esters 194/195 result (Scheme 25)"" . 

Sucdnimido Ketone, 6 To 17.22 g (0.17 mole) of succinimide in a 1000 mL round bottomed flask was added 150 mL of THF and the suspension stirred at 65°C until the succinimide was dissolved. In a separate 250 mL flask 20.4 g (0.18 mole) potassium f-butoxide was suspended in 120 mL of THF and the suspension sonicated for 10 min to give a cloudy solution which was added dropwise to the stirred... 

Rate differences observed between the same bromophenylcarbene (241) when prepared by two different routes, diazirine photolysis and the reaction of benzylidene dibromide with potassium f-butoxide, vanish when a crown ether is added to the basic solution in the latter experiment. In this case the complexing potassium bromide is taken over by the crown ether, and selectivity towards alkenes reaches the values of the photolytic runs (74JA5632). 

While high polymers of /3-lactones can also be formed by cationic polymerization, most of the commercial production seems to be by the anionic route. Carboxylate salts such as sodium acetate or benzoate are commonly the initiators, but other nucleophiles, such as triethylamine, betaine, potassium f-butoxide, aluminum and zinc alkoxides, various metal oxides and tris(dimethylamino)benzylphosphonium chloride (the anion of which is the initiator), are of value. Addition of crown ethers to complex the counter cation increases the rate of reaction. When the reaction is carried out in inert but somewhat polar organic solvents, such as THF or ethyk acetate, or without solvent, chain propagation is very fast and proceeds without transfer reactions. 

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