Ethers Experimental Procedure

Iodine, concentrated aqueous ammonia solution, ethanol, diethyl ether. Experimental Procedure... 

A solution of estradiol (38, 15 mg) in methanol-OD (4 ml) and one drop of 10% deuteriosulfuric acid in deuterium oxide is heated under reflux for 5 days. After cooling the reaction mixture is diluted with ether, washed with dilute sodium bicarbonate solution and water, then dried over anhydrous sodium sulfate. Evaporation of the ether gives crystalline 2,4-d2-estradiol (39, 15 mg, 99%), mp 173-175° (ether-hexane), exhibiting 82% isotopic purity and only one aromatic hydrogen by NMR. (For an experimental procedure describing the exchange of aromatic protons under Clemmensen conditions, see section III-D.)... 

Experimental procedures A The substance is dissolved or suspended in ether and treated with ethereal diazomethane. B The substance is dissolved in methanol (or ethanol, acetone, chloroform) and reacted with ethereal diazomethane. C A solution or suspension of the substance in ether is mixed with ethereal diazomethane,... 

Thermolysis of the parent compound in refluxing bis(2-methoxyethyl) ether gives carbazole (4)331 (see Houben-Weyl, Vol.E6a, p967(f, with an experimental procedure),... 

Pure di-2-propenylzinc2,8,9 10, bis(2-methyl-2-propenyl)zinc11 or di-2-butenylzinc11 are best prepared by the metal exchange between dimethylzinc and the appropriate triallylborane, which is produced in situ from the Grignard reagent and boron trifluoride-diethyl ether complex. The purification is accomplished by distillation, for experimental procedure, see ref 2, p619. 

This series of reagents is characterized by the use of metals under the appropriate conditions. In this regard, a mixture of zinc dust and titanium tetrachloride in ether provided a useful synthesis of vinyl sulphides43, with the possibility of further substitution alpha to the sulphur atom, as outlined in equation (16). The reaction is easy to carry out and gave yields of 49 to 87%, although the authors do not provide much detail of their experimental procedure and of the purity (chemical or stereochemical) of their products. 

On the other hand, the method of Mukaiyama can be succesfully applied to silyl enol ethers of acetic and propionic acid derivatives. For example, perfect stereochemical control is attained in the reaction of silyl enol ether of 5-ethyl propanethioate with several aldehydes including aromatic, aliphatic and a,j5-unsaturated aldehydes, with syir.anti ratios of 100 0 and an ee >98%, provided that a polar solvent, such as propionitrile, and the "slow addition procedure " are used. Thus, a typical experimental procedure is as follows [32e] to a solution of tin(II) triflate (0.08 mmol, 20 mol%) in propionitrile (1 ml) was added (5)-l-methyl-2-[(iV-l-naphthylamino)methyl]pyrrolidine (97b. 0.088 mmol) in propionitrile (1 ml). The mixture was cooled at -78 °C, then a mixture of silyl enol ether of 5-ethyl propanethioate (99, 0.44 mmol) and an aldehyde (0.4 mmol) was slowly added to this solution over a period of 3 h, and the mixture stirred for a further 2 h. After work-up the aldol adduct was isolated as the corresponding trimethylsilyl ether. Most probably the catalytic cycle is that shown in Scheme 9.30. 

The reaction of acceptor-substituted carbene complexes with alcohols to yield ethers is a valuable alternative to other etherification reactions [1152,1209-1211], This reaction generally proceeds faster than cyclopropanation [1176], As in other transformations with electrophilic carbene complexes, the reaction conditions are mild and well-suited to base- or acid-sensitive substrates [1212], As an illustrative example, Experimental Procedure 4.2.4 describes the carbene-mediated etherification of a serine derivative. This type of substrate is very difficult to etherify under basic conditions (e.g. NaH, alkyl halide [1213]), because of an intramolecular hydrogen-bond between the nitrogen-bound hydrogen and the hydroxy group. Further, upon treatment with bases serine ethers readily eliminate alkoxide to give acrylates. With the aid of electrophilic carbene complexes, however, acceptable yields of 0-alkylated serine derivatives can be obtained. 

Experimental Procedure 4.2.10. Cycloaddition of an Acylcarbene Complex to an Enol Ether Ethyl 5-Ethoxy-2-trifluoromethyl-4,5-dihydro-3-furoate [1417]... 

Catalytic hydrogenation is hardly ever used for this purpose since the reaction by-product - hydrogen chloride - poses some inconveniences in the experimental procedures. Most transformations of acyl chlorides to alcohols are effected by hydrides or complex hydrides. Addition of acyl chlorides to ethereal solutions of lithium aluminum hydride under gentle refluxing produced alcohols from aliphatic, aromatic and unsaturated acyl chlorides in 72-99% yields [5i]. The reaction is suitable even for the preparation of halogenated alcohols. Dichloroacetyl chloride was converted to dichloro-... 

This experimental procedure must be followed carefully to avoid partial decomposition of ethyl a-(hydroxymethyl)acrylate. The reaction is stopped rapidly after the addition of the carbonate solution (5 min) to prevent formation of high molecular weight by-products which result from transesterification and Michael addition, both of which occur in the basic medium. However, about 25% of the product is lost. Addition of diethyl ether during cooling minimizes side reactions. 

Reagents. All reagents used in experimental procedures were of the highest grade commercially available. Methylene chloride, hexane, and ethyl ether used... 

V. Ketones / 134 Selectivity / 134 Stereochemistry / 135 Ether formation / 136 Experimental procedures / 136... 

The same experimental procedure was used for further N-alkylation reactions of 2,4-bis(trimethylsilyloxo)thieno[3,2-d]pyrimidine-2,4-diones 271. Thus, reaction of 271 with 2-acetoxyethyl acetoxymethyl ether, 2-(acetoxymethoxy)propane-l,3-dibenzoate, and benzyloxymethyl acetate gave the respective 1- and 3-alkylated derivatives 274 and 275, 276 and 277, and 278 and 279 (90MI1 94JHC305 94MI2, 94MI3). ... 

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