Benzyltrimethylammonium Ethoxide

Three hundred and thirty-five grams of the 25% ethanolic solution of benzyltrimethylammonium ethoxide (0.43 mole) is placed under nitrogen in a 3-1. three-necked flask equipped with a gas inlet tube, a gas-tight modified Hershberg stirrer (Note 1), and a gas outlet tube fitted with a thermometer. All stoppers and rubber connections are wired in place with 16-gauge copper wire. There is obtained by evaporation at 40° (Note 9) under reduced pressure (Note 10) 97 g. (0.40 mole) of the ethoxide containing an equivalent of ethanol. The vacuum is broken with dry nitrogen. 

This method is more satisfactory than storage of the benzyltrimethylammonium ethoxide monoethanolate. The excess ethanol is removed as necessary. 

This solution contains 24—30% benzyltrimethylammonium ethoxide (2.1-2.7 moles), as determined by titration with 0.1 N hydrochloric acid, using methyl red as indicator. This represents a yield of 67-90%. An additional 270 00 g. of solution is obtained by filtration of the residual mixture under nitrogen. To ensure rapid filtration, a filter aid, such as Filtered (Note 7), must be employed. The filtrate contains 24-30% benzyltrimethylammonium ethoxide (0.3-0.7 mole). The total yield is 89-100%. The solutions are stored under nitrogen and refrigeration in bottles sealed with rubber stoppers which are wired in place (Note 8). 

The procedure described is adapted from the preparation outlined by Meisenheimer.3 The method has been applied by the authors to the preparation of benzyltrimethylammonium meth-oxide, tetramethylammonium ethoxide, dibenzyldimethylammo-nium methoxide, bisisopropylbenzyltrimethylammonium meth-oxide and benzyl trie thylammonium ethoxide. 

Dehydrohalogenation Benzyltrimethylammonium mcsitoate. r-Butylamine. Calcium carbonate. j Uidine. Diazabicyclo[3.4.0]nonene-5. N.N-Dimethylaniline (see also Ethoxy-acetylene, preparation). N,N-Dimelhylformamide. Dimethyl sulfoxide-Potassium r-but-oxide. Dimethyl sulfoxide-Sodium bicarbonate. 2,4-Dinitrophenylhydrazine. Ethoxy-carbonylhydrazine. Ethyldicyclohexylamine. Ethyidiisopropylamine. Ion-exchange resins. Lithium. Lithium carbonate. Lithium carbonate-Lithium bromide. Lithium chloride. Methanolic KOH (see DimethylTormamide). N-PhenylmorphoKne. Potassium amide. Potassium r-butoxide. Pyridine. Quinoline. Rhodium-Alumina. Silver oxide. Sodium acetate-Acetonitrile (see Tetrachlorocyclopentadienone, preparation). Sodium amide. Sodium 2-butylcyclohexoxide. Sodium ethoxide (see l-Ethoxybutene-l-yne-3, preparation). Sodium hydride. Sodium iodide in 1,2-dimethoxyethane (see Tetrachlorocyclopentadienone, alternative preparation) Tetraethylammonium chloride. Tri-n-butylamine. Triethylamine. Tri-methyiamine (see Boron trichloride). Trimethyl phosphite. 

The optimal base for closure to epoxide 2 is sodium ethoxide in ethanol, as potassium hydroxide in ethanol, sodium or potassium carbonate in ethanol, or benzyltrimethylammonium hydroxide in ethanol resulted in the formation of a complex mixture of decomposition products arising mainly from deprotonation at carbon. 

TMG (1), as well as benzyltrimethylammonium hydroxide (Triton B) in pyridine and sodium ethoxide in ethanol, was found to work as base catalyst in the cyclopropanation of steroid skeletons controlled by intramolecular Sn2 reaction [70]. Thus, 6-oxo-3a,5-cyclo-5ot-steroids were given in high yields for the reaction of 3p-tosyloxy (or -chloro)-6-oxo derivatives (Table 4.8). 

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