Potassium fcrf-butoxide

The preparation of potassium fcrf-butoxide is carried out according to a procedure already described.2 Particular attention should be paid to the precautions in handling potassium. 

In the case of HWE reactions of phosphonate esters containing a charge-stabilizing electron-withdrawing group, for example, as in trimethyl phosphono-acetate, the carbanion is often generated by reaction with potassium fcrf-butoxide, sodium hydride, n-butyllithium or similar base. Direct reaction with an aldehyde or ketone then gives the ( )-a,P-unsaturated ester as the major product (see Protocol 6). The nature of the phosphonate (see Section 3), and the substitution of the aldehyde or ketone, can influence the stereochemical outcome of these reactions as can, to a lesser extent, the reaction temperature and solvent.16... 

Several interesting 1,2,4-triazole fused-ring systems have been reported. Reaction of aryl nitriles with 4-amino-l,2,4-triazine-3-thiones in the presence of potassium fcrf-butoxide afforded... 

The synthesis of 1,1-diiodocyclopropane is carried out via addition of diiodocarbene (car-benoid) to alkenes the carbene, in turn, is generated from iodoform and a base. The process is realized using phase-transfer catalysis,125,126 (33%125 or 50%126 aqueous sodium hydroxide and a quaternary ammonium salt, typically benzyltriethylammonium chloride, as a catalyst) or in the presence of potassium fcrf-butoxide in tert-butyl alcohol108,1 >4-l25- 127- 128, e.g. formation of 1. 

Carrying out dehydrohalogenations with a bulky base such as potassium fcrf-butoxide (r-BuOK) in S r butyl alcohol (r-BuOH) favors the formation of the less substituted alkene ... 

Dialkylation The monoalkylacetoacetic ester shown above still has one appreciably acidic hydrogen, and, if we desire, we can carry out a second alkylation. Because a monoalkylacetoacetic ester is somewhat less acidic than acetoacetic ester itself due to the electron-donating effect of the added alkyl group, it is usually helpful to use a stronger base than ethoxide ion for the second alkylation. Use of potassium fert-butoxide is common because it is a stronger base than sodium ethoxide. Potassium fcrf-butoxide, because of its steric bulk, is also not likely to cause transesterification. 

The Corey-Chaykovsky reaction will be used to cyclopropanate your chalcone from Experiment 61. The reaction involves the reaction of trimethylsulfoxonium iodide and potassium fcrf-butoxide in anhydrous dimethylsulfoxide (DMSO). The reaction is stirred at room temperature for 1 hr. For example, frans-chalcone (1,3-diphenyl-2-propen-l-one) produces an 88% yield of the cyclopropanated product. You will analyze your product by NMR and infrared spectroscopy. 

Referring to the spectra on the website for Figures 10.5 and 10.7-10.9, calculate the percentage compositions of the mixtures of isomeric methylbutenes obtained from the reaction of 2-bromo-2-methylbutane with potassium hydroxide and potassium fcrf-butoxide. In the spectra of the mixtures, the integration of the resonances in the region of 8 5.0 ppm has been electronically amplified in the upper stepped line so that the relative areas of the two multi-plets in that region can be more accurately measured. 

With potassium /m-butoxide in tetrahydrofuran, the dibromodihydro-3//-l-benzazepines 7 (R1 = H, F, Cl) undergo syn dehydrobromination to synthetically useful alkenyl bromides, e.g. 8 (R1 = Cl), accompanied by small amounts of debrominated materials, e.g, 9 (R1 = Cl), and the 3-fcrf-butyl ethers, e.g. 10b(R1 = Cl, R2 = -Bu).78 In contrast, with sodium hydroxide, or with sodium methoxide in dioxane/methanol, the yields of bromo compounds 8 decrease, and significant amounts of the methyl ethers, e.g. 10a (R1 = Cl R2 = Me), arc produced. A mechanistic rationale for these reactions has been offered. 

Mesityl oxide Methanol Methylamine N- M et hy lformam i de Methyl isobutyl ketone 2-Aminoethanol, chlorosulfonic acid, nitric acid, ethylenediamine, sulfuric acid Beryllium dihydride, chloroform, oxidants, potassium fcrf-butoxidc Nitromethane Benzenesulfonyl chloride Potassium ferf-butoxide... 

Dolenc and Plesnicar reported an alternative procedure for the preparation of l-(tert-butylperoxy)benziodoxoles 120 from the corresponding chlorobenziodoxoles 119 and fcrf-butyl hydroperoxide in the presence of potassium tcrf-butoxide in THF (Scheme 2.42) [286]. 

Di-0-benzyl-3,4-0-isopropylidene-D-mannitol was ring closed to afford a 9 1 cis/trans mixture of 189 in high yield by (Swern) oxidation and radical cyclization of the dialdehyde using samarium iodide in fcrf-butanol. The cis-diastereoisomer was selectively converted into a cis-cyclic sulfate which underwent cleavage upon treatment with potassium tert-butoxide to afford a cyclo-... 

The laboratory assistant should prepare the mixture by combining trimethylsulfoxonium iodide (Me3S(0)l, 5.90 g 26.8 mmol) with potassium ferf-butoxide (KO-fcrf-Bu, 3.00 g 26.7 mmol). Grind the mixture so that the two compounds are equally distributed and mixed with each other. One gram of this mixture provides 3.0 mmol of methylide/g or 0.6 mmole/0.2 g. Store the mixture in a desiccator. 

A high concentration of a strong base in a relatively nonpolar solvent is used to carry out the dehydrohalogenation reaction. Such combinations as sodium methoxide in methanol, sodium ethoxide in ethanol, potassium isopropoxide in isopropanol, and potassium ferf-butoxide in fcrf-butanol or dimethyl sulfoxide (DMSO) are often used. 

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