N-Bromoacetamide

Reaction of Olefins with N-Bromoacetamide-Hydrogen Fluoride... 

Addition of fluorohalides to double bonds preparation of 9a-bromo-ll/3-fluoro-17q , 21-dihydroxypregn-4-ene-3, 20-dione 21-acetate by reaction with N-bromoacetamide-hy drogen fluoride, 458... 

To a solution of 2.4 g of pregna-1,4,9(11)-triene-21-ol-3,20-dione-[17o ,16a-d] -2 -methylox-azoline 21 -acetate in 24 ml of tetrahydrofuran, 12.8 ml of 0.46N perchloric acid are added at 15°C under stirring. N-bromoacetamide (1.1 g) is then added to the mixture which is kept far from light, and stirred for 4 hours at room temperature. After lowering the temperature to 10°C, a saturated solution of sodium bisulfite is added in order to decolorize the mixture, which is then poured into 120 ml of Ice water. A product separates, which is collected by filtration, washed with water and then dried, thus obtaining 2.81 g of crude 9a-bromo-pregna-... 

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. 

In contrast with the behaviour of typical vinylphosphonic acid derivatives, the carbon-carbon double bond in the 1,2-oxa-phospholene (167) is remarkably unreactive towards a broad spectrum of reagents including electrophiles, most epoxidizing and organometallic reagents, as well as to dipolar addition reactants. Exceptional reagents are, however, N-bromoacetamide (NBA), ozone, dimethyllithiumcuprate, and sodium-naphthalene. 

The related syn diol epoxide isomers were synthesized from the 1,2- and 7,8-dihydrodiols of 5-MC by reaction with N-bromoacetamide in moist DMSO followed by base-catalyzed cyclization by the usual Method I procedures (60). 

Bromine, reaction with phenylacetylene and sodium hydroxide to give phenylbromoethyne, 46, 86 N-Bromoacetamide, as reagent for bromofluorination of 1-heptene, 46,10... 

N-bromoacetamide org chem CHsCONHBr Needlelike crystals with a melting point of I02-I05°C soluble in warm water and cold ether used as a brominating agent and in the oxidation of primary and secondary alcohols. en bro mo-3 sed-3,mTd ... 

Notes Used for allylic and benzylic brominations (Wohl-Zieeler Reaction). With moist DMSO the reagent is useful for bromohydrin formation, providing trans addition of bromine and water. Can brominate alpha to carbonyl in carbonyl (carboxyl)-containing compounds. With DMF useful for aromatic bromination of activated aromatic rings, such as phenols, aromatic ethers, aniline derivatives and activated heterocyclic compounds. For similar chemistry, see also NBA, N-Bromoacetamide. 

Cathylates are stable to oxidation with potassium chromate in acetic acid and with N-bromoacetamide,60 acetylation and formylation with 85 % formic acid at room temperature.59 They are cleaved by bases to give the parent alcohol, carbon dioxide and ethanol. 

The bottle is flushed with dry nitrogen, and a slow stream of nitrogen passes through the bottle during all subsequent operations to ensure the exclusion of atmospheric moisture (Note 2). N-Bromoacetamide (80 g., 0.58 mole) is added (Note 3). The... 

Satisfactory sources of chemicals are N-bromoacetamide, Arapahoe Chemicals, Boulder, Colorado 1-heptene, Aldrich Chemical Co. hydrogen fluoride, Matheson Co. 

N-Bromoacetamide (NBA) is also a useful positive bromine equivalent Thus NBA in the presence of H2O or LiOAc/HOAc has resulted in the functionalization of 11,12-dihydrobenzo[e]pyrene (Scheme 69).135 NBA has also been employed in conjunction with H2O for the regio- and stereo-selective hydro-bromination of the 10,11 double bond of avermectin Bla, a complex antibiotic containing five double bonds.136... 

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