A-Chloro ethers

Bromination of a-chloro ethers proceeds readily and often gives 90—95% yields (24). 

The present method gives better yields and is a simpler procedure than those described previously The ease of preparation of a-chloro ethers enables one to effectively remove a protecting methyl group from a phenol2 a-Chloroanisole is used to produce phenoxycarbene, a reactive intermediate in cyclopropane synthesis8... 

Secondary benzylic bromides, allylic bromides, and a-chloro ethers can undergo analogous reactions using ZnBr2 as the catalyst.1 2 Primary iodides react with silyl... 

ChT.ORODTTSOPROPYLPHOSPHINE, 48, 47 a-Chloro ethers as intermediates in de-methylation of anisoles, 47, 24 Chloroform, condensation with benz-aldehyde, 48, 27... 

Strategies for preparing mixed, acyclic acetals on insoluble supports include the oxidative haloalkoxylation of support-bound enol ethers (Entry 6, Table 6.1) and the acid-catalyzed reaction of alcohols with resin-bound enol ethers [627]. Alternatively, resin-bound a-chloro ethers can be converted to mixed acetals by reaction with alcohols or phenols in the presence of strong bases (KO/Bu, HOfBu, DMF, 5 h) [550,628]. Polystyrene-bound a-(phenylseleno)ethers react with aliphatic alcohols under slightly acidic conditions (NIS, TfOH, DCM/dioxane (1 1), 0°C to 20 °C, 1 h) to yield mixed, acyclic acetals [628],... 

However, many aldehydes react with alcohols in the presence of an excess of hydrogen chloride to give a-chloro ethers ... 

Exercise 16-28 Write equations to show how you would convert 2-butanone to 2-methoxy-2-methylthiobutane by way of the corresponding a-chloro ether. 

The basis for assuming that III should react metathetically with a Grignard reagent was that it is a hemiacetal chloride, and the simple chlorides of this type, namely, the a-chloro ethers, are known to react in the manner of Equation (5). This type of. reaction has been used50 for the synthesis of a-substituted ethers, and also constitutes one of the... 

The reaction of the Reformatsky reagents with a-chloro ethers gives j8-alkoxycarboxylic acid esters 73, 290, 291, 294, 526). For example,... 

The reactions of a-chloro ethers with phenols and phenol ethers in the presence of zinc afford diarylmethanes. For example,... 

Two block copolymers of trimethylcellulose-b-polyoxyethylene have been reported (139). The trimethylcellulose blocks containing one a-chloro ether end were treated with silver hexafluoroantimonate, AgSbF, in THF solution between — 10 C and + 23 C to facilitate a living cationic THF polymerization of polyoxytetramethylene blocks, as shown in Fig. 8. 

Alkoxy ketones.8 In the presence of ISi(CH3)3 or (CH3)3SiOTf, silyl enol ethers react with a-chloro ethers to give (3-alkoxy ketones selectively. Evidently ISi(CH3)3 activates only the C—Cl bond. Similarly, the reaction of silyl enol ethers with a-chloro sulfides gives rise only to P-alkylthio ketones. 

Stabilized carbonyl ylides such as 3.52 have been prepared by the treatment of the silyl substituted a-chloro ethers 3.51 with fluoride ions under neutral conditions. 

The carbonyl ylides are trapped in a [2-1-3]-cycloaddition with activated alkenes or alkynes. For example, the reaction of the a-chloro ether 3.56 with cesium fluoride (CsF) in the presence of dimethyl fumarate gives only the trans cycloaddition product 3.57, while the reaction with dimethyl maleate gives exclusively the cis-isomer 3.58 (Scheme 3.24). 

The rather unreactive arylcadmium reagents, ArCdCl, do react satisfactorily with both primary and secondary a-bromo esters and with secondary allylic bromides, but curiously they react much more poorly with allyl and benzyl bromide, and a-chloro ethers ca. 40% yields) no coupling occurs using primary alkyl bromides. Finally, the old Wurtz-Fittig mediodology, whereby an aryl bromide and an alkyl iodide are coupled in the presence of elemental sodium, can sometimes lead to acceptable yields (40-60%) no rearrangement products are formed, and it is likely that free radicals are not involved. 

Reactions with Alkyl Halides.— The in situ generation and reaction of chlorodi-phenylphosphine (2) with a-chloro-ethers gives good yields of a-alkoxyalkylphosphine oxides (20). The phosphine (2) is made from phosphorus trichloride and benzene, and the sequence looks like a very convenient one-pot procedure - the dangers of certain chloro-ethers aside ... 

Gross, H., Engelhardt, G., Freiberg, J., Burger, W., and Costisella, B., a-Halo ethers. Part 31. Michaelis-Arbuzov reactions with a-chloro ethers and a-chloro amines, Liebigs Ann. Chem., 707, 35, 1967. 

Sodium fluoride [1, 1073-1074, before reference]. Sodium fluoride suspended in nonaqueous tetramethylene sulfone, acetonitrile, or DMF has been found to exchange halogen readily with carboxylic acid chlorides, a-chloro ethers, trichloro-methanesulfenyl chloride, POCl3, etc.2 ZG. W. Tullock and D. D. Coffman, J. Org.. 25, 2016 (1960)... 

Perhydropyrazino[2,3-fc]pyrazine (13) has been obtained by reacting ethylenediamine with the a-chloro ethers 11and 12. These ethers act effectively as a source of glyoxal. Analogously, diacetyl reacts with ethylenediamine to give the dimethyl derivative 14. ... 

Iminium salts. N-Silyl derivatives of secondary amines react with carbonyl compounds afford a-siloxyamines. On further treatment with Me,SiCl, iminium chlorides are obtained. Trimethylsilyl triflate is superior to Me SiCl since it can induce the transformation in the cases of enolizable aldehydes. a-Chloro ethers are more reactive than carbonyl compounds, enabling the preparation of vinylogous Viehe salts. 

Condensation of 2-(benzyloxy)ethanol with a mixture of the hydrate and methyl hemiacetal of methyl glyoxalete 638 gave a hemiacetal, which was converted directly with methanesulfonyl chloride to a-chloro ether 639. It condensed with silylated uracil, 5-fluorouracil, and A -acetylcytosine,... 

Dianions of /8-keto-esters can be alkylated with a-chloro-ethers to give 5-alkoxy-jS-keto-esters in ca. 70% yield. These compounds serve as useful alternatives to y5-unsaturated-/8-keto-esters in the Robinson annelation reaction.Clean nucleophilic displacement of bromine from y-bromoacetoacetates can be effected by prior protection of the keto-ester system as the sodium enolate. ... 

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