Grignard reagent and ethylene oxide

Problem 14.31 (a) Give the product of the S 2-type addition of CjHjMgBr to ethylene oxide, (b) What is the synthetic utility of the reaction of Grignard reagents and ethylene oxide 4... 

Grignard reagent and esters, 6, 32 Grignard reagent and ethylene oxide, , 54... 

Crganosodium compounds behave similarly to the Grignard reagent with ethylene oxide. 2-(a-Thienyl)-1-ethanol and y.y.y-triphenylpropyl alcohol are prepared from 2-chlorothiophene and trityl chloride, respectively, through the sodium compounds. 

The Grignard reagent from 2-thenyl chloride can be obtained by the use of the "cyclic reactor.However, rearrangement occurs in its reaction with carbon dioxide, ethyl chlorocarbonate, acetyl chloride, formaldehyde, and ethylene oxide to 3-substituted 2-methylthio-phenes, Only in the case of carbon dioxide has the normal product also been isolated. 

Grignard reagents react with oxetane, a four-membered cyclic ether, to yield primary alcohols, but the reaction is much slower than the corresponding reaction with ethylene oxide. Suggest a reason for the difference in reactivity between oxetane and ethylene oxide. 

Condensation of Grignard reagents with alkyl-substituted ethylene oxides is fairly complex, particularly if the epoxides involved are asymmetric and massively substituted. The reaction course depends also on the structure of the Grignard reagent, and obviously on experimental conditions used for the condensation. 45 ... 

Hudrlik, P. F. Ahmed, M. E. Roberts, R. R. Hudrlik, A. M. Reactions of (triphenylsilyl) ethylene oxide with Grignard reagents (and with MgBr2). A reinvestigation./. Org. Chem. 1996, 61, 4395-4399. 

Scheme 7 displays a possibility of the synthesis of chiral 2-arylpropionic acids via the oxidative tranformation of (7 )-3-aryl-l-butenes. The requisite chiral olefins may be obtained by transition metal-catalyzed asymmetric coupling between a benzylic Grignard reagent and vinyl bromide (93 % optical yield) [28] or, more attractively, asymmetric hydrovinylation of an aromatic olefin with ethylene. The asymmetric combination of styrene and ethylene, giving the adduct 25 in 95 % ee, has been performed on a 10-kg scale with a dinuclear Ni catalyst formed from ( -allyl)NiCl2 and a unique chiral dimeric aminophosphine obtainable from (/ )-myrtenal and (5)-l-phenylethylamine [7a],... 

Phenylethanol, which has the aroma of oil of roses, is used in perfumes. Write equations to show how 2-phenylethanol can be synthesized from bromobenzene and ethylene oxide, using a Grignard reagent. 

The Sn2 reaction between a Grignard reagent and an epoxide works reasonably well when the epoxide is ethylene oxide. However, when the epoxide is substituted with groups that provide steric hindrance, a competing reaction can dominate, in which an allylic alcohol is produced. Propose a mechanism for this transformation and use the principles discussed in Section 8.13 to justify why the allylic alcohol would be the major product in this case below. 

We saw an example of nucleophilic ring opening of epoxides in Section 15.4, where the reaction of Grignard and organolithium reagents with ethylene oxide was presented as a synthetic route to primary alcohols ... 

Prepare a Grignard reagent from 24 -5 g. of magnesium turnings, 179 g. (157 ml.) of n-heptyl bromide (Section 111,37), and 300 ml. of di-n-butyl ether (1). Cool the solution to 0° and, with vigorous stirring, add an excess of ethylene oxide. Maintain the temperature at 0° for 1 hour after the ethylene oxide has been introduced, then allow the temperature to rise to 40° and maintain the mixture at this temperature for 1 hour. Finally heat the mixture on a water bath for 2 hours. Decompose the addition product and isolate the alcohol according to the procedure for n-hexyl alcohol (Section 111,18) the addition of benzene is unnecessary. Collect the n-nonyl alcohol at 95-100°/12 mm. The yield is 95 g. 

Section 15 4 Grignard and organolithium reagents react with ethylene oxide to give primary alcohols... 

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