Sodium ethynyl

The methylheptenones are intermediates for the synthesis of linalool (3). A continuous ethynylation with sodium hydroxide and /V-methy1pyrro1idinone has been developed (eq. 3) (29). 

A ( )-Enol-l 1-acetates are formed by distillation of acetic anhydride in the presence of / -toluenesulphonic acid. Another procedure employed for the synthesis of enol benzoates involves treatment with benzoic anhydride and triphenyl methyl sodium or ethynyl sodium. Suitable procedures utilizing a diluent have been developed for the enol esterification of a 20-ketone without affecting an 11-ketone. 

Acetylene is passed for 1 hr through a mixture consisting of 0.5 g (72 mg-atoms) of lithium in 100 ml of ethylene-diamine. A solution prepared from 1 g (3.5 mmoles) of rac-3-methoxy-18-methylestra-l,3,5(10)-trien-I7-one and 30 ml of tetrahydrofuran is then added at room temperature with stirring over a period of 30 min. After an additional 2 hr during which time acetylene is passed through the solution the mixture is neutralized with 5 g of ammonium chloride, diluted with 50 ml water, and extracted with ether. The ether extracts are washed successively with 10% sulfuric acid, saturated sodium hydrogen carbonate and water. The extract is dried over sodium sulfate and concentrated to yield a solid crystalline material, which on recrystallization from methanol affords 0.95 g (87%) of rac-3-methoxy-18-methyl-17a-ethynyl-estra-l,3,5(10)-trien-17jB-ol as colorless needles mp 161°. 

The stereochemistry of the product resulting from the reaction of a 17-keto steroid with ethylidenetriphenylphosphorane is different from that of the 17-ethylidene steroids obtained by dehydration of 17a-ethyl-17/ -hydroxy compounds, Wolff-Kishner reduction of A -20-keto steroids or by sodium-alcohol or sodium-ammonia " reductions of 17-ethynyl carbinols. These latter products have generally been assumed to possess the trans configuration (C-21 methyl away from the bulk of the ring system) because of anticipated greater stability. The cis configuration for... 

Both sodium acetylide in xylene (Air Reduction Corporation) and lithium acetylide-ethylenediamine complex (Foote Mineral Co.) are now commercially available, and have been used successfully for the ethynylation of 17-keto steroids. 

Isotellurazoles la-e were first prepared by coupling ethynyl ketones with hydroxylamine-O-sulfonic acid and K2Te in aqueous solution of sodium acetate... 

By using sodium amide in ammonia, ethynyl-Ai-methylpyrazoles 15a-c were synthesized by dehydrohalogenation of dichlorides 13a-c, 14a-c in 60-85 % yields, calculated on acetylpyrazoles 12a-c (Table VTT). 

In 1973, the unexpected transformation of 4-chloroethynyl-l,3,5-trimethylpy-razole under the action of sodium amide in liquid ammonia into 5-aminomethyl-4-ethynyl-l,3-dimethylpyrazole in 85% yield was reported (73IZV2166). Within... 

It is neeessary to emphasize that the direet amination of the methyl group at position 5 of pyrazoles is impossible. Neither 1,3,5-tiimethyl- nor4-ethynyl-l,3,5-trimethylpyrazole undergoes sueh transformations under the reaetion eonditions and starting materials are reeovered nearly quantitatively. Moreover, 4-bromo-ethynyl-l,3,5-trlmethyl- and 4-iodoethynyl-l,3,5-trimethylpyrazole with sodium amide in ammonia exehange the halogen for metal almost quantitatively and in this respeet are similar to phenylehloroaeetylene (Seheme 102). 

A reaction of sodium azide with l,4-dichlorobut-2-yne (diacetylene equivalent) has been described (89CB1175). When the monosubstitution product is treated with sodium hydroxide in methanol, 4-ethynyl-l//-l,2,3-tiiazole (93) is formed. 

The problems of handling liquid ammonia are alleviated in this modification of the sodium acetylide generation procedure. Finely divided sodium is prepared in boiling toluene, the toluene is replaced by THF, and a direct reaction between sodium and acetylene is carried out. The resulting sodium acetylide is employed in ethynylation reactions as before. 

The most convenient method for the preparation of sodium acetylide appears to be by reaction of acetylene with sodium methylsulfinyl carbanion (dimsylsodium). The anion is readily generated by treatment of DMSO with sodium hydride, and the direct introduction of acetylene leads to the reagent. As above, the acetylide may then be employed in the ethynylation reaction. 

Methylsulfinyl carbanion (dimsyl ion) is prepared from 0.10 mole of sodium hydride in 50 ml of dimethyl sulfoxide under a nitrogen atmosphere as described in Chapter 10, Section III. The solution is diluted by the addition of 50 ml of dry THF and a small amount (1-10 mg) of triphenylmethane is added to act as an indicator. (The red color produced by triphenylmethyl carbanion is discharged when the dimsylsodium is consumed.) Acetylene (purified as described in Chapter 14, Section I) is introduced into the system with stirring through a gas inlet tube until the formation of sodium acetylide is complete, as indicated by disappearance of the red color. The gas inlet tube is replaced by a dropping funnel and a solution of 0.10 mole of the substrate in 20 ml of dry THF is added with stirring at room temperature over a period of about 1 hour. In the case of ethynylation of carbonyl compounds (given below), the solution is then cautiously treated with 6 g (0.11 mole) of ammonium chloride. The reaction mixture is then diluted with 500 ml of water, and the aqueous solution is extracted three times with 150-ml portions of ether. The ether solution is dried (sodium sulfate), the ether is removed (rotary evaporator), and the residue is fractionally distilled under reduced pressure to yield the ethynyl alcohol. 

Dana2ol was prepared from 4.32 grams of 17a-ethynyl-2-hydroxymethylene-4-androsten-17(3-ol-3-one, 1.00 gram of hydroxylamine hydrochloride, 1.12 grams of fused sodium acetate and 135 ml of acetic acid. To a 500 ml, 3-necked flask, equipped with a sealed Hershberg-type stirrer, a reflux condenser and a stopper, was added the above androstenone derivative in 300 ml of 95% ethanol. Stirring was commenced and a slurry of fused sodium acetate and hydroxylamine hydrochloride in glacial acetic acid was added. 

The treatment of o-bromophenyl ethynyl ketones with sodium hydrogen teUuride follows a similar pathway giving tellurochromone. ... 

Even with lithium- or sodium amide in liquid ammonia, specific deproton anon at the ethynyl group is expected, but in this polar solvent subsequent nucleophilic substitution of Br ... 

Homologues of ethoxyacetylene can be obtained by reaction of the metallated ethynyl ether in liquid ammonia with primary alkyl bromides and iodides 167]. Because of their better solubiliiy, the lithium compounds are preferred over their sodium and potassium analogues, lithium ethoxyacetylide is generated from the readily accessible 2-bromovinyl ethyl ether and two equivalents of lithium amide. This starting compound is obtained as a mixture of the E-and Z-isomer. When this mixture is heated with powdered KOH, only the Z-isomer is converted into ethoxyethyne. Alkali amides are able to conven both isomers into ethoxyethyne and its alkali compounds. A possible explanation for this violation of the "rule of... 

Sodium ethoxide in ethanol (compare the preparation of PhG=CH, exp. 4) seems an unsuitable system for the dehydrohalogenation because ethynyl thioethers smoothly give adducts ROCH=CHSR under these conditions [167]. 

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