Bromoacetamidation

The Q. j-unsaturated ester and amide 942 is prepared by the Pd-catalyzed Wittig-type reaction of the bromoacetate or bromoacetamide 941 with aldehydes and BU(Asf785],... 

Bromine monofluoride [13863-59-7], BrF, can be prepared by the direct reaction of Br2 and F2, but because it readily disproportionates it has never been prepared in pure form (57). However, BrF can be prepared in situ by the reaction of Br2 with AgF in benzene (58) or by the reaction of A/-bromoacetamide and HF in ether (59). BrF adds to simple alkenes at room temperature to give products of trans-addition. Bromine trifluoride [7787-71-5], BrF, can be formed from gaseous fluorine and Hquid bromine (60). Bromine pentafluoride [7789-30-2], BrF, is formed from the reaction of BrF vapor with gaseous fluorine at 200°C (60). The tri- and pentafluorides are commercially available. As strong fluorinating agents they are useful in... 

A/-bromoacetamide [79-15-2] CH3CONHB1 102-105 hrominating agent, oxidizes 1° and 2° alcohols, irritant 117... 

A(-Bromoacetamide [79-15-2] M 138.0, m 102-105 , 107-109 , 108 (anhyd). Possible contaminant is CH3CONBr2. Recrystd from CHCl3/hexane (1 1, seed if necessary) or water and dried over CaCl2. [Oliveto and Gerold Org Synth Coll Vol IV 104 1963). 

Bromination is selective for the 3-ketone under these mild conditions. Other reagents will also do this e.g. A/-bromoacetamide, mono- and dibromo-... 

A iD-Corticoids have been important intermediates since it was shown ° that substitution at C-9 enhances anti-inflammatory activity. These olefins are usually obtained from 11a- or 11)5-alcohols, and consequently several refined methods have been devised for effecting this dehydration. It is desirable that such methods be compatible with the presence of A" -3-ketone and 17-hydroxy functions. The first direct procedure for which high yields were claimed was described in a patent issued to Upjohn. According to this method, the alcohol (11a or )5) is treated first with A-bromoacetamide in pyridine, then with sulfur dioxide. Recently it has been claimed " that the A-haloamide/sulfur dioxide method gives results superior to other methods, although the methanesulfonyl chloride/sulfur dioxide procedure (see below) apparently was not compared (see also ref. 94). 

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

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

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 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... 

The method of Fried and Sabo for the in situ preparation of hypobromous acid from A-bromoacetamide (or A-bromosuccinimide) in aqueous dioxane or acetone containing perchloric acid is commonly used, e.g., (81) (82). 

The elements of bromine azide have been added to steroid olefins. The addition can be rationalized as proceeding through a positive bromonium ion under the ionic conditions of Hassner and Boerwinkle (bromine plus sodium azide and hydrochloric acid in nitromethane-dichloromethane) or Ponsold (A-bromosuccinimide or A-bromoacetamide in chloroform contain-... 

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. 

Ladenheim and Morawetz [23] also showed that the reactivity of the carboxylate units in partially ionized poly(methacrylic acid) (PMA) toward BrCH2COO in the bromine displacement reaction was greatly diminished, while the reaction proceeded at an appreciable rate with uncharged p-bromoacetamide [23]. This inhibition of the reaction of the polyanion with a small anionic reagent can be attributed to the electrostatic repulsion between the polymer and the reagent. 

BrN3 13973-87-0) see Cefoxitin bromoacetaldehyde diethyl acetal (C6H 3Bt02 2032-35-1) see Domiodol bromoacetaldehyde ethylene acetal (C4H7Br02 4360-63-8) see Carbimazole IV-bromoacetamide... 

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