Dibromoethyl Acetate

A solution of 160 g. (1.0 mole) of bromine in 90 ml. of carbon tetrachloride is added with agitation to a solution of 86 g. (1.0 mole) of 

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The final variation of the Feist-Benary furan synthesis encompasses reactions of 1,3-dicarbonyls with 1,2-dibromoethyl acetate (52). For example, treatment of ethyl acetoacetate (9) with sodium hydride followed by addition of 52 at 50°C yields dihydrofuran 53. The product can be easily converted into the corresponding 2-methyl-3-furoate upon acid catalyzed elimination of the acetate, thus providing another strategy for the synthesis of 2,3-disubstituted furans. 

Several significant pyrrole syntheses involve the formal tricomponent cyclization of type III ace (equation 126). The Hantzsch pyrrole synthesis involves a dicarbonyl compound, an a -halo ketone and ammonia or an amine. The mechanistic pattern is similar to that involved in the Knorr synthesis (Section 3.06.3.4.1). In addition to a-halo ketones and a-haloal-dehydes, compounds such as 1,2-dichloroethyl acetate, 1,2-dibromoethyl acetate and 1,2-dichloroethyl ethyl ether can serve as a -haloaldehyde equivalents (equation 127) (70CJC1689, 70JCS(C)285>. It is believed that the initial step in these reactions is the formation of a stabilized enamine from the amine and the /3 -dicarbonyl compound. A structural ambiguity... 

Dibromoethyl acetate is a useful a-bromoacetaldehyde surrogate in this reaction (Equation (39)) <90SC1923>. 

Dibromoethane 1,2-Dibromoethane c/s-1,2- Di brom oethene 1rans-1,2-Dibromoethene 1,2-Di brom 0-1-ethoxyethane 1,2-Dibromoethyl acetate... 

D. a-Allyl- -bromoelhyl ethyl ether. The same apparatus is used as in the preparation of allylmagnesium bromide. The flask is charged with an amount of the Grignard solution (part C) equivalent to 2.78 moles of allylmagnesium bromide (or chloride) and cooled in an ice bath. A solution of 580 g. (2.5 moles) of o , 3-dibromoethyl ethyl ether (part B) in an equal volume of anhydrous ether is added slowly with stirring over a period of 3-4 hours. The mixture is allowed to stand overnight and is then hydrolyzed with 75 ml. of 20% acetic acid followed by 500 ml. of water. The ether layer is separated, washed with four 100-ml. portions of 10% aqueous sodium bicarbonate solution followed by four 100-ml. portions of saturated aqueous sodium chloride solution, dried over 100 g. of anhydrous calcimn sulfate, and distilled under reduced pressure. The yield of colorless a-allyl-/3-bromoethyl ethyl ether is 370-396 g. (77-82% based on the a, 3-dibromoethyl ethyl ether), b.p. 72-75°/21 mm., 1.4600-1.4606. 

Dibromoethyl silicon dichloride, (CH2Br.CH2)2SiCl2, is produced by heating together a mixture of two molecular proportions of ethylene bromide with 1 mol. of silicon tetrachloride dissolved in ether, and four molecular proportions of sodium and a little ethyl acetate. The product is a dark brown oil. Doubt has recently been expressed as to the existence of this compound. ... 

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