Alkylation with ethyl bromide

Thus, the condensation product of cyclohexanone and ethyl cyanoacetate (125) affords the intermediate (126) for the synthesis of cyclobarbital (112) on alkylation with ethyl bromide. The condensation product of cycloheptanone (127) affords the starting... 

Marchalin et al. b8 have cyclized compounds 290 to pyridopyrimidines (291) thermally or in alcoholic solution in the presence of sodium ethoxide. The 2-mercapto group of compound 291 (R = COOEt) was alkylated with ethyl bromide. IR and MS data are given. 

The 2-mercapto group of pyridopyrimidinone 121 (R = COOEt) was alkylated with ethyl bromide (81CCC2428). 

There are a few examples of the the formation of aminoorganotin(IV) compounds from diamino- or diorgano-tin(II) compounds. The tin(II) diamine (16-1) can be alkylated with ethyl bromide or iodide to give the ethyltin halide diamides (16-2).23... 

Synthesis of repaglinide involves condensation of an appropriately substituted and chi-rally pure benzylamine derivative with an appropriately substituted phenylacetic acid derivative (7) followed by saponification. The reported process for the key intermediate (7) described a five-step process with an overall yield of about 30% of theory (Scheme 23.4) We undertook development of an alternative synthetic strategy to prepare 7 and developed an efficient and commercially feasible synthesis starting from 2-hydroxy-4-methylbenzoic acid (9) in two steps. Thus, 9 was first alkylated with ethyl bromide in a polar aprotic solvent and in the presence of an inorganic base to afford ethyl 2-ethoxy-4-methylbenzoate... 

Equation (4) was used to prepare an optically active a-ethyl-a-phenyl-b-propiolactone starting from a substituted ethyl cyanoacetate. This compound was alkylated with ethyl bromide, hydrogenated to the amino ester, resolved in the form of an optically active isomer, and hydrolyzed to the amino acid ... 

An early application of this reaction to the preparation of barbiturates starts by the condensation of the ketone, I21, with ethyl cyanoacetate by Knoevenagel condensation. Alkylation of the product (122) with ethyl bromide by means of sodium ethoxide affords 123. Condensation of this intermediate with guanidine in the presence of sodium ethoxide gives the diimino analog of a barbiturate (124). Hydrolysis affords vinbarbital (111). > ... 

The a.a-diethylacetoacetamide used as starting material was obtained by converting diketene with aqueous ammonia to acetoacetamide and alkylating twice with ethyl bromide in the presence of sodium alcoholate. 

Silver fluoborate, reaction with ethyl bromide in ether, 46, 114 Silver nitrate, complexing with phenyl-acetylene, 46, 40 Silver oxide, 46, 83 Silver thiocyanate, 45, 71 Sodium amide, in alkylation of ethyl phenylacetate w ith (2-bromo-ethyl)benzene, 47, 72 in condensation of 2,4-pentanedione and 1 bromobutane to give 2,4-nonanedione, 47, 92 Sodium 2 ammobenzenesulfinate, from reduction of 2 mtrobenzenesul-finic acid, 47, 5... 

Primary alkyl chlorides can be converted to bromides with ethyl bromide, V-methyl-2-pyrrolidinone and a catalytic amount of NaBr," with LiBr under... 

The alkyl halide (ethyl bromide in the above equation) can react further with the primary amine produced to give a secondary amine and with that to form a tertiary amine and finally a quaternary ammonium salt. Quaternary ammonium hydroxides are very strong bases like sodium hydroxide. Tetramethylammonium hydroxide is a very important chemical used in the manufacture of semiconductors and other electronic industry products. 

Carbanion 239 derived from vinyl sulfone 238 was shown to be alkylated regiospecifi-cally at the a-carbon atom The carbanions 240 and 241 derived from <5-ketosulfones were shown to be alkylated at both a- and y-carbons . Alkylation of 240 gave a-alkylated products predominantly, while the a/y ratio varied markedly by change of the alkylating agent in the reaction with 241. For example, methylation with methyl iodide gave the products in the a/y ratio of 72 28, while the a/y ratio was 27 73 in the ethylation with ethyl bromide ... 

Preparation of the quaternary anticholinergic agent benzilonium bromide (47) is begun by conjugate addition of ethylamine to methylacrylate, giving aminoester 42. Alkylation of 42 with methyl bromo-acetate leads to diester 43, which is transformed into pyrrolidone 44 by Dieckmann cyclization, followed by decarboxylation. Reduction of 44 by lithium aluminum hydride leads to the corresponding amino-alcohol (45). Transesterification of alcohol 45 with methyl benzilate leads to 46. Benzilonium bromide (47) is obtained by alkylation of ester 46 with ethyl bromide. 2... 

With ethyl bromide as solvent a brief, exploratory study [77] showed that the rates and DPs were more irreproducible than with other alkyl halides, and this was ascribed, at least partly, to the relatively high dissociation constant of ethyl bromide to ethylene and hydrogen bromide. No evidence was obtained whether ethyl bromide itself is a co-catalyst, and the putative co-catalyst in the reaction was residual water and possibly traces of t-BuBr formed from HBr and isobutene. Experiments with [C4H8] = 0.11-0.92 mole/1, [TiCl4] (2.7-11.2) x 103 mole/1, T = -38° to -103° showed that EDP = 5.5 0.5 kcal/ mole that below about -60° the DP is almost independent of monomer concentration and that kjkp = 2 x 10 4 at -63° and 8 x 10"5 at -71°. 

The short Sanofi route to irbesartan (3) is outlined in Scheme 9.6. Dihydroimidazolone 27, which is prepared from the reaction of 1-amino-cyclopentanecarboxylic acid ester (25) with ethyl pentanimidate (26) in the presence of acetic acid in refluxing xylene, is alkylated with biphenylbenzyl bromide 18 in the presence of sodium hydride in DMF to give 28. Finally, the synthesis of irbesartan (3) is completed by the tetrazole formation from reaction of the nitrile group of 28 with tributyltin azide in refluxing xylene. [See Bernhart et al. (1993a, b).]... 

Alkyl halides, acyl halides, anhydrides, and related substances. It was discovered as early as 1861 by Rcboul and Luurenool<4t> that epicblorohydrin may be caused to react with ethyl bromide on heating in a sealed tube to an elevated temperature. The product isolated from this condensation was ]-broJHo-3-chloro-2-ethoxyprt>pane. Some year later Paalli6 extended this reaction to include also methyl iodide, ethyl iodide, n-propyl iodide, and isopropyl iodide do2-propunol was formed. 

The reaction of methyl ester of D-alanine 185 with 4-methoxy-2-nitrobenzenesulfonyl chloride 186 in presence of ethyl diisopropylamine gave the sulfonamide 187, which was alkylated with allyl bromide 188 to afford 189 (Scheme 41). Ozonolysis of 189 resulted in the formation of aldehyde 190, and the subsequent reductive cyclization with zinc and AcOH led to the benzothiadiazepine 120 through intramolecular reductive alkylation. Using similar reaction sequence, the 1,2,5-thiadiazepines 191 and 192 were also synthesized <2003JME1811>. 

In the first step p-nitrophenol is alkylated on its phenolic oxygen with ethyl bromide. 

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