Potassium /-Butoxide-Hexamethylphosphoric Triamide

Related Reagents. w-Butyllithium-potassium f-butoxide Potassium Amide Potassium Hexamethyldisilazide Potassium f-butoxide-benzophenone Potassium f-butoxide-r-butyl Alcohol Complex /t-butyllithium-Potassium it t-butoxide Potassium t-butoxide-18-crown-6 Potassium r-butoxide-dimethyl Sulfoxide Potassium f-butoxide-hexamethylphosphoric Triamide Potassium Diisopropylamide Potassium f-heptoxide Potassium Hydroxide Potassium 2-methyl-2-butoxide. 

Related Reagents. A(,A(-Diitiethylformaniide N,N -Dimethylpropyleneurea Dimethyl Sulfoxide Hexam-ethylphosphoric Triamide-Thionyl Chloride Lithium Chloride-Hexamethylphosphoric Triamide l-Methyl-2-pyrrolidinone Potassium t-Butoxide-Hexamethylphosphorie Triamide Potassium Hydride-Hexamethylphosphorie Triamide Potassium Hydroxide-Hexamethylphosphoric Triamide A(,A( -Tetramethylethylenediamine. 

The Roussel group has described recently a novel method for the synthesis of 2,2-dimethyl-A" -3-keto steroids. Thus addition of potassium t-butoxide to a solution of 19-nortestosterone (25) in tetrahydrofuran containing methyl iodide and hexamethylphosphorous triamide at —70° affords the 2,2-dimethyl compound (26) in good yield.Methylation of A" -3-ketone by the classical conditions, namely addition of methyl iodide to a solution of the steroid and potassium /-butoxide, leads to the 4,4-dimethyl product. 

Intramolecular cyclization of 6-(mesyloxymethyl)bicyclo[4.4.0]dcc-l-cn-3-one using lithium diiso-propylamide produced almost exclusively the y-alkylation product tricyclo[5.3.1.01,6]undec-5-en-4-one (17), together with a trace amount of the 2-alkylation product tricyclo[5.3.1 016]undec-5-en-8-one (18).17 Surprisingly, the a-alkylation product 18 was the major product when the cyclization was carried out using potassium tert-butoxide.17 The preference for y-alkylation over a-alkylation can be rationalized by the Hammond postulate which favors y-alkylation due to the less reactant-like transition state when lithium diisopropylamide is used. Alternatively, when potassium /ert-butoxide and 18-crown-6 in hexamethylphosphoric triamide is used, the reactivity of the enolate anion is significantly enhanced. As a result, the transition state becomes reactant-like so that a-alkylation is the predominant process.17... 

Cesium fluoride-Tetraalkoxysilanes, 69 Hexamethylphosphoric triamide, 142 Methyl acrylate, 183 a-Methylbenzylamine, 185 Methyl vinyl ketone, 193 Potassium t-butoxide, 252 Potassium f-butoxide-Xonotlite, 254 Potassium fluoride-Alumina, 254 Tin(II) trifluoromethanesulfonate, 301 Titanium(IV) chloride, 304 Trityl perchlorate, 339 Vinyl(triphenyl)phosphonium bromide, 343... 

Heating 3-methylene-2,3-dihydrotellurophene at 50° for one hour with a mixture of potassium /er/.-butoxide, hexamethylphosphoric acid triamide, and THF produced 3-methyl tellurophene1. 

Methyltellurophene1 To a mixture consisting of 10 m/ of hexamethylphosphoric triamide, 10 m/ of tetrahydrofuran, 0.5 g (6 mmol) of tert.-butanol, and 1.1 g (10 mmol) of potassium rerf.-butoxide are added 9.7 g (50 mmol) of 3-methylene-2,3-dihydrotellurophene. The mixture is heated at 50° for 1 h, water is added, the mixture is extracted with diethyl ether, the extract is washed with water, dried with anhydrous magnesium sulfate, filtered, and the solvent is evaporated. The residue is distilled under vacuum yield 8.7 g (90%) h.p. 72"/14 torr. 

Bromination of an olefin and double dehydrobromination of the resulting 1,2-dibromide is a classical method for the generation of 1,3-dienes (Table 1). Bromination of a double bond can be done with molecular bromine or, more conveniently, with pyridinium bromide perbromide . A variety of bases has been employed for dehydrobromination. While potassium hydroxide and sodium methoxide have been used for a long time, lithium carbonate-lithium chloride in DMF or hexamethylphosphoric triamide (HMPA) works well in many cases . Double dehydrobromination with hindered bases such as potassium r-butoxide or diazabicyclononene (DBN) and diazabicycloundecene (DBU) give good results. 

DEHYDROHALOGENATION Amidines, bicyclic. N-Bromosuccinimide. 1,5-Dia-zabicyclo[4.3.01 nonene-5. Diethylamine. Dimethyl sulfoxide. Hexamethylphosphoric triamide. Lithium bromide. Potassium r-butoxide. Sodium amidc-Sodium r-but-oxide. Tetra-n-butylammonium bromide. Triethylamine. 

Threefold addition of 1-bromo-2-chlorocyclopropene to hexaradialene afforded a complicated mixture of stereoisomers which, on treatment with potassium tert-butoxide in tetrahy-drofuran under nitrogen, was converted to the symmetrical tricyclopropa[ r,/ , ]triphenylene (12) in 20% yield. The adduct 13 obtained upon repetitive addition of l-bromo-2-chlorocyclo-propene to hericene was aromatized with potassium /erf-butoxide in dimethylformamide/ hexamethylphosphoric triamide (5 1) to afford tricyclopropatriptycene (14) in 50% yield. The mono- and bis-adducts of hericene were analogously converted to cycloproparenes in 65% and 69% yield, respectively. 

Dehydrohalogenation Alumina, see Sulfur tetrafluoride. Alumina-Potassium hydroxide. Cesium fluoride. l,5-Diazabicyclo[4.3.0]nonene-5. l,4-Diazabicyclo[2.2.2]octane. 1,5-Diazabicyclo[5.4.0]undecene-5. Dimethylaminotrimethylstannane. Dimethyl sulfoxide. Hexamethylphosphoric triamide. Lithium chloride. Lithium dicyclohexylamide. Magnesium oxide. Potassium r-butoxide. Potassium fluoride. Potassium triethylmethoxide. Pyridine, see Nitrosyl chloride. Silver fluoride. Silver nitrate. Sodium amide. Sodium bicarbonate, see Nitryl iodide. Sodium isopropoxide. Triethylamine, see Sulfur dioxide. 

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