Ai-bromosuccinimide

Side-Chain Derivatization. Reaction of thiophene with aqueous formaldehyde solution in concentrated hydrochloric acid gives 2-chloromethylthiophene [765-50-4]. This relatively unstable, lachrymatory material has been used as a commercial source of further derivatives such as 2-thiopheneacetonitrile [20893-30-5] and 2-thiopheneacetic acid [1918-77-0] (24). Similar derivatives can be obtained by peroxide, or light-catalyzed (25) halogenation of methylthiophenes, eg, Ai-bromosuccinimide/benzoylperoxide on 2-, and 3-methylthiophenes gives the corresponding bromomethylthiophenes. 

Alkenes react with Ai-bromosuccinimide (NBS) to give allylic bromides. NBS serves as a source of Br2, and substitution occurs by a free-radical mechanism. The reaction is used for synthetic puiposes only when the two resonance fonns of the allylic radical aie equivalent. Otherwise a mixture of isomeric allylic bromides is produced. 

Oxiranes are usually prepared from halohydrins. A general method of obtaining chloroalcohols from olefins is by the addition of hypochlorous acid formed in situ form -chloramides or fert-butyl hypochlorite. Bromoalcohols are produced from alkenes with Ai-bromosuccinimide or iV-bromoacetamide, while iodoalcohols are prepared with iodine in the presence of oxidants (iodic acid, oxygen, and nitrite). 

In some cases, six-membered rings can be involved in ring-opening reactions. For example, the reaction of 4,6-O-benzylidene glucopyranoside 34 with Ai-bromosuccinimide (NBS) in the presence of barium carbonate leads to the corresponding 4-0-benzoyl-6-bromo-6-deoxy... 

There are many report in the literature on the effects of chain conformation [19-25]. One example is radical bromination of poly(methyl styrene) [20] with Ai-bromosuccinimide-benzoyl peroxide or Br2-K2C03-light. NMR spectroscopy shows differences in reactivities of the methyl groups in the 3 and 4 positions on the benzene rings between isotactic and atactic polystyrenes [20]. 

Bis(trimethylsilyl)carbinols have been reported to react with Ai-bromosuccinimide in carbon tetrachloride to give the corresponding a-haloacyl silanes in moderate yields (Scheme 34). ... 

New pyridinium gemini amphiphiles with ethane-l,2-dithiol spacer have been synthesized by regioselective electrophilic cobromination of R-olefins [46]. Firstly, ethane-1,2-dithiol and Ai-bromosuccinimide on reaction with R-olefins (dodecene, tetradecene, hexadecene, and octadecene) gave the respective l,2-bis(2-bromoalkylthio)ethane. Subsequently, the bromoalkylthio... 

Abbreviations Ac acetyl Bn benzyl BSP 1-benzenesulfinyl piperidine BTIB bis(trifluoroacetoxy)iodobenzene DAST (diethylamino)sulfur trifluoride DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTSF dimethyl(methylthio)sulfonium tetrafluoroborate DMTST dimethyl(methylthio)sulfonium triflate DTBMP 2,6-Ai-tert-butyl-4-methylpyridine DTBP 2,6-di-tert-butylpyridine DTBPl 2,6-di-tert-butylpyridinium iodide FDCPT l-fluoro-2,6-dichloropyridinium triflate FTMPT l-fluoro-2,4,6-trimethylpyridinium triflate IDCP iodonium dicollidine perchlorate IDCT idonium dicollidine triflate LPTS 2,6-lutidinium p-toluenesulfonate LTMP lithium tetramethylpiperidide Me methyl MPBT S-(4-methoxyphenyl) benzenethiosulflnate NBS A-bromosuccinimide NIS A-iodosuccinimide NlSac A-iodosaccharin PPTS pyridinium p-toluenesulfonate TBPA tris(4-bromophenyl)ammoniumyl hexachloroantimonate Tf trifluoromethanesulfonyl TMTSB methyl-bis(methylthio)sulfonium hexachloroantimonate TMU tetramethylurea Tr trityl TTBP 2,4,6-tri-tert-butylpyrimidine. 

This amine, structurally related to N,N-diethylaniline but more easily purified, has been used for dehydrobromination of the product of allylic bromination of vitamin Ai ester (1) with N-bromosuccinimide to produce vitamin Aj. ester. ... 

Several rare examples of such abstractions using triphenylmethyl tetrafluoroborate (Khand et ai, 1969) and Al-bromosuccinimide (Efraty and Maitlis, 1967) are known. 

---