Succinimide, bromination chlorination

OH — X. Pi. carbohydrate hydroxyl group can be replaced by halogen (bromine, chlorine, iodine) by treatment in DMF with 2 eq. each of triphenylphosphine and an N-halosuccinimidc. The by-products are succinimide and triphenylphosphine oxide. Yields are generally high. Primary hydroxyl groups can be selectively replaced in the presence of secondary hydroxyl groups. 

V-Chlorosuccinimide [128-09-6] mp 150—151°C, forms orthorhombic crystals and has a chlorine-like odor it is prepared from succinimide and hypochlorous acid (114,115). Because of its powerhil germicide properties, it is used ia disiafectants for drinking water. Like its bromine derivative, it is also a halogenating agent. 

The substitution reactions of 3-acetamidothiophene have been extensively investigated. From the bromination with A-bromosuc-cinimide and from the chlorination with sulfuryl chloride or A-chloro-succinimide only the 2-isomers were obtained, the structure of which... 

Bromination of a-ergocriptine 2 with commercial N-bromosuccinimide (NBS) can lead to the formation of traces of a mysterious by-product, finally identified as 2-chloro-a-ergocryptine 4. Investigation of NBS indicated that it contains up to 1.5 % of chlorine (probably as N-chloro-succinimide, NCS). This chlorination occurs only in the presence of NBS, never with NCS alone ... 

Kojic acid was brominated at position 6 with bromine water4 the 2-(chloromethyl) derivative of kojic acid was brominated with N-bromo-succinimide,87 and chlorinated with sulfuryl chloride and aluminum chloride,88 in both cases probably at C6. The C-benzoylation89 and C-acetylation90 of kojic acid, likewise at C6, was accomplished by Woods using a modification of the Friedel-Crafts reaction. The 2-carboxyethyl side chain was introduced at C6 in a reaction with 2-bromopropionic acid.91... 

Boron trifluoride and boron trifluoride-diethyl ether complex can be used as a source of fluoride ions in the presence of hypobromites and hypochlorites, e.g. methyl hypobromitc, tert-butyl hypobromite, methyl hypochlorite in carbon tetrachloride at 25 C. The addition of bromine monofluoride" and chlorine monofluoride" to various alkenes is accompanied by the formation of the corresponding alkoxybromides and alkoxychlorides which hinder the isolation of the halofluorinated products.57 jV-Bromo- and A -chloro-substiluted alkyl- and arylamines. -amides, and -imides, A -chloro-A,-methylamine, A -bromo-A -methylamine, A -chloro-A, /V-dimethylamine, A-bromo-A.A-dimethylamine, ACV-dichloro-A -methylamine, V,fV-dibromo-,V-mcthylaminc, A -bromosuccinimide, -V-chlorosuccinimide, Af-bromoacct-amide, A.A -dichlorourethane, can be used in the reaction instead of the hypohalites. The reactions with various alkenes conducted in dichloromethane at room temperature in the presence of boron trifluoride-diethyl ether complex produce bromofluoro and chlorofluoro addition products in 40-80 % yield. However, the reactions are complicated by the addition of A -halo-succinimides and Af.A-dichlorourcthane to the C = C bonds.58... 

Thiiranes can be formed directly and stereospecifically from 1,2-disubstituted alkenes by addition of trimethylsilylsulfenyl bromide, formed at -78 C from reaction of bromine with bis(trimethylsilyl) sulfide (Scheme 7).12 A two-step synthesis of thiiranes can be achieved by addition of succinimide-A/-sulfe-nyl chloride or phthalimide-A -sulfenyl chloride to alkenes followed by lithium aluminum hydride cleavage of the adducts (Scheme 8).13 Thiaheterocycles can also be formed by intramolecular electrophilic addition of sulfenyl chlorides to alkenes, e.g. as seen in Schemes 914 and 10.13 Related examples involving sulfur dichloride are shown in Schemes 1116 and 12.17 In the former case addition of sulfur dichloride to 1,5-cyclooctadiene affords a bicyclic dichloro sulfide via regio- and stereo-specific intramolecular addition of an intermediate sulfenyl chloride. Removal of chlorine by lithium aluminum hydride reduction affords 9-thiabicyclo[3.3.1]nonane, which can be further transformed into bicyclo[3.3.0]oct-1,5-ene.16... 

The direct nuclear chlorination, bromination, or iodination of pyrazines is usually done with elemental halogen or /V-halogeno succinimide but direct fluorination... 

Cyclohexene (161), for example, reacts with NBS in the presence of light to give 3-bromocyclohexene (162) in 45% yield by the radical substitution mechanism presented in Section 11.9.1, once diatomic bromine is generated. The reaction of NBS and toluene (methylbenzene PhMe) gives benzyl bromide. The mechanism that involves succinimide will not be elaborated. Both NBS and NCS react as if bromine or chlorine were being added to the reaction, but they are readily available and easy to handle. 

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