F butoxide

Uranium hexa-/ f/-butoxide is an exception and does not react with water (55). References 3 and 5 discuss chemical properties of alkoxides. In some cases hydrolysis is reversible, but usually it is not (23,56). 

Zirconium alkoxides behave similarly in regard to thermal stability. The series zirconium methoxide [28469-78-5] zirconium ethoxide [18267-08-8] zirconium isopropoxide [2171 -98 ] zirconium /r /f-butoxide [2081 -12-1] shows decreasing thermal stability. 

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. 

A detailed study of ROMP of disubstituted norbornadienes (e.g., 2,3-dicarbo-methoxynorbornadiene or 2,3-bis(trifluoromethyl)norbornadiene (NBDF6) [124] showed that they are polymerized by Mo(f-butoxide) initiators in a well-behaved living manner to give essentially monodisperse homopolymers that are... 

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. 

An exothermic reaction was observed at this point. Too rapid addition of the f-butoxide solution to the benzene solution will lead to loss of product by frothing. 

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. 

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