9-Bromo-9- methylene

Acetyl-nitrosamino)- 1280 3-Acetyl-2-trimethylsilyl- 156 3-(Bromo-methylen)- 155... 

Shi and coworkers have reported that the reaction of benzaldehydes with but-3-yn-2-one in the presence of boron (III) bromide provides the a-bromo methylene aldol product (115) in high selectivity. This approach provides the analogous P-bromo Baylis-Hillman adducts (Equation 70) [73]. 

Carbonylation of halides in the presence of primary and secondary amines at I atm affords amides[351j. The intramolecular carbonylation of an aryl bromide which has amino group affords a lactam and has been used for the synthesis of the isoquinoline alkaloid 498(352], The naturally occurring seven-membered lactam 499 (tomaymycin, neothramycin) is prepared by this method(353]. The a-methylene-d-lactam 500 is formed by the intramolecular carbonylation of 2-bromo-3-alkylamino-l-propene(354]. 

Alkoxyall l Hydroperoxides. These compounds (1, X = OR , R = H) have been prepared by the ozonization of certain unsaturated compounds in alcohol solvents (10,125,126). 2-Methoxy-2-hydroperoxypropane [10027-74 ] (1, X = OR , R" = methyl), has been generated in methanol solution and spectral data obtained (127). A rapid exothermic decomposition upon concentration of this peroxide in a methylene chloride—methanol solution at 0°C has been reported (128). 2-Bromo-l-methoxy-l-methylethylhydroperoxide [98821-14-8]has been distilled (bp 60°C (bath temp.), 0.013 kPa) (129). Two cycHc alkoxyaLkyl hydroperoxides from cyclodecanone have been reported (1, where X = OR R, R = 5-oxo-l, 9-nonanediyl) with mp 94—95°C (R" = methyl) and mp 66—68°C (R" = ethyl) (130). Like other hydroperoxides, alkoxyaLkyl hydroperoxides can be acylated or alkylated (130,131). 

PE, 4, 25, 587 <76JCS(P2)276) Furan-2-carbonitrile, 3-bromo- H NMR, 4, 558 <71BSF990) Furan-2-carbonitrile, 2-hydro-5-methylene- H NMR, 4, 577 75TL36I9, 70TL777) Furan-3-carbonitrile... 

A suspension of 17a,21-dihydroxypregna-4,9(ll)-diene-3,20-dione 21-acetate (0.77 g) and iV-bromoacetamide (0.3 g) in anhydrous methylene dichloride (40 ml) is added over 2-3 min with stirring to a mixture of anhydrous hydrogen fluoride (10.19 g), and anhydrous tetrahydrofuran (18 g) in a polyethylene bottle at —80° (acetone-dry ice). After 1 hr at —80° the reaction mixture is kept for a further 1 hr at 0° and then added cautiously to an excess of an ice-cold solution of sodium carbonate. Extraction with methylene dichloride and crystallization from acetone-hexane furnish 9a-bromo-ll -fluoro-17a,21-dihydroxypregn-4-ene-3,20-dione 21-acetate (0.69 g), mp 205-208°, raised by several crystallizations from acetone-hexane to 215-217° [aju 142° (CHCI3) max 240-242 mju (e 15,500). 

Addition of dimethylsulfoxonium methylide to the a-face of A -20-ketones, A -5a-H-ketones and A " -3-ketones results in the formation of the corresponding 16a,17a-methylene (1), la,2a-methylene-5a-H (2) and la,2a-methylene-A" steroids (3), respectively. Smooth reaction is also observed in the presence of 2-chloro and 2-bromo substituents in the A -5a-H-3-ketone series.Yields of 90% are obtained within a reaction period of 5 hr at room temperature. A A -3-keto system in (1) is not attacked under these conditions. 

Ciamician reported the formation of 3-halogenopyridines in low yield from the reaction of pyrryl potassium with chloroform, or bromo-form, in ether. Similar reactions of pyrrole with benzal chloride and methylene iodide gave 3-phenylpyridine and traces of pyridine, respectively. These reactions were later reinvestigated by Alexander... 

Bromo-5-methylene-2(5//)-furanone 133 was obtained from the /3-angelica lactone 129 by using mild simple methods that combine bromination and dehy-drobromination or debromination processes accomplished in a convenient order, as illustrated in Scheme 41 (94T12457). 

Thermal cycloadditions of butadiene to 3-bromo- 133 and 3-methoxy-5-methylene-2(5//)-furanones 220 were studied (95TL749). These systems contain substituents at C3 capable of stabilizing also a possible radical intermediate, influencing hereby the rate and/or the course of the reaction. Thus, the reaction of 133 and 220, respectively, with butadiene at 155°C afforded mixtures of the expected 1,4-cycloadducts 221 and 222, respectively, and of the cyclobutane derivatives... 

When methylene chloride was used as a solvent, it was found that 28 are obtained in minor amounts, while the dominating product is the -coordinated chloro-carbyne species [(> -Tp )Mo(CO)2(=CCl)], whose yield increases abruptly with substitution in the pyrazol-l-yl fragments (3-methyl-, 3,4,5-trimethyl-, and 3,5-dimethyl-4-chloro derivatives) [90AX(C)59,95JCS(D) 1709]. The tungsten analog can be prepared similarly. The chlorocarbyne molybdenum complex follows also from the reaction of the parent anion with triphenylsulfonium cation but conducted in dichloromethane. The bromo- and iodocarbyne derivatives are made similarly. 

To a solution of 6.78 g of 6a-fluoro-9a-bromo-11 (3,17a,21-trihydroxy-16a-methyl-1,4-preg-nadiene-3,20-dione-21 -acetate in 175 ml of acetone was added 6.78 g of potassium acetate and the resulting suspension was heated under reflux for a period of 17 hours. The mixture was then concentrated to approximately 60 ml volume at reduced pressure on the steam bath, diluted with water and extracted with methylene chloride. The methylene chloride extracts were combined, washed with water, dried over anhydrous sodium sulfate and evaporated. 

A mixture of 1.38 grams of the above compound and 15 cc of dioxane was treated with 1.9 cc of a 0.5 N aqueous solution of perchloric acid and 600 mg of N-bromoacetamide, adding the latter in the dark, in three portions, in the course of half an hour and under continuous stirring. It was then stirred for a further 1% hours in the dark, then the excess of reagent was decomposed by the addition of aqueous sodium bisulfite solution and ice water was added the product was extracted with methylene chloride, washed with water, dried over anhydrous sodium sulfate and the solvent was evaporated under reduced pressure, thus giving a yellow oil consisting of the 16,21-diacetate of 6a-fluoro-9a-bromo-16o-hydroxy-hydrocortisone which was used for the next step without further purification. 

A solution of N-(2-aminobenzvl)-1-phenyl-2-metKylaminoethanol-1 was prepared by the reaction of a-bromo-acetophenone and (2-nitrobenzyl)methylamine, followed by hydrogenation of the nitro group by means of nickei on diatomaceous earth at room temperature and reduction of the CO group by means of sodium borohydride. The intermediate thus produced was dissolved in 100 ml of methylene chloride and introduced dropwise into 125 ml of sulfuric acid at 10° to 15°C. After a short standing, the reaction mixture was poured onto ice and rendered alkaline by means of a sodium hydroxide solution. Dy extraction with ether, there was obtained 1,2,3,4-tetrahydro-2-methyl-4-phenyl-8-amino-iso-quinoline. The base is reacted with maleic acid to give the maleate melting point of the maleate 199° to 201°C (from ethanol). 

The solvents were evaporated in vacuo, and the residue was taken up in 80 ml of 3M hydrochloric acid. After addition of 220 ml of water, the insoluble material was filtered off, washed with 100 ml of water and then dried. The insoluble material weighed 9.5 g and was mainly unreacted bromo compound. The filtrate was reacted with 50 ml of 7 M NaOH, extracted three times with methylene chloride (50 m -t 2 x 25 ml portions), dried over potassium carbonate, and then evaporated. The yield of residue was 26.8 g which corresponds to 71.4% of the theoretical yield. This residue was a colorless solidifying oil and was dissolved in 200 ml chloroform. Hydrogen chloride was bubbled in until a sample of the solution tested acidic to wet pH indicator paper. A precipitate was obtained and recovered by filtration. The precipitate was washed with chloroform and dried. The melting point was determined to be from 246 Cto247.5°C. 

Problem 13.22 3-Bromo-l-phenyl-l-propene shows a complex NMR spectrum in which the vinyli< proton at C2 is coupled with both the Cl vinylic proton (J - 16 Hz) and the C3 methylene protons (/ = 8 Hz). Draw a tree diagram for the C2 proton signal, anc account for the fact that a five-line multiplet is observed. 

The double bond is readily introduced into dihydrodibenzoxepins following the halogenation of one or two of the activated methylene groups. 7-Bromo-6,7-dihydrodibenz[/>,[Pg.19]

The oil, which is heavier than water, is separated, and the aqueous layer is extracted with three 50-ml. portions of methylene chloride. The oil and extracts are combined, dried over anhydrous sodium sulfate, and distilled from a Claisen flask with an indented neck. Colorless l-bromo-2-fluorobenzene is collected at 58-59°/17 mm. or 156—157°/760 mm. weight 45-47 g. (73— 75% based on o-bromoaniline) d 1.5320-1.5325. 

Polymerization of 4-bromo-6,8-dioxabicyclo[3.2.1 ]octane 2 7 in dichloromethane solution at —78 °C with phosphorus pentafluoride as initiator gave a 60% yield of polymer having an inherent viscosity of 0.10 dl/g1. Although it is not described explicitly, the monomer used seems to be a mixture of the stereoisomers, 7 7a and 17b, in which the bromine atom is oriented trans and cis, respectively, to the five-membered ring of the bicyclic structure. Recently, the present authors found that pure 17b was very reluctant to polymerize under similar conditions. This is understandable in terms of a smaller enthalpy change from 17b to its polymer compared with that for 17a. In the monomeric states, 17b is less strained than 17a on account of the equatorial orientation of the bromine atom in the former, whereas in the polymeric states, the polymer from 17b is energetically less stable than that from 17a, because the former takes a conformation in which the bromine atom occupies the axial positioa Its flipped conformation would be even more unstable, because the stabilization by the anomeric effect is lost, in addition to the axial orientation of the methylene group. 

Isobutylene-based elastomers include HR, the copolymer of isobutylene and isoprene, halogenated HR, star-branched versions of these polymers, and the terpolymer isobutylene-p-methylene styrene-bromo-p-methyl styrene (BIMS). A number of recent reviews on isobutylene-based elastomers are available [33-35]. 

Bromo-3-methyl-2-methylene-1 -phenyl-1,2-dihydroquinoxaline 2-Bromomethyl-6-methyl-3-... 

The fact that we have three olefinic hydrogens means that our compound is a primary olefin, the fact that the other two carbons are both methylene carbons means that our substituent, bromine, is terminal. Thus the only possibility we have is that we are dealing with 4-bromo-1-butene (try to find another isomer that fits ). But this simple molecules has a highly complex proton spectrum, which can only be interpreted completely (exact chemical shift, coupling constants) by spectrum simulation. 

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