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N-Bromosuccinimide is a chemical reagent used in electrophilic additions and radical substitution reactions in synthetic organic chemistry. In Wohl-Ziegler reaction, it is involved in allylic and benzylic bromination reaction. It is also used in the alfa-bromination of carbonyl derivatives. In the Hofmann rearrangement, it is used in the presence of a strong base, such as 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) reacts with primary amides to produce a carbamate. It oxidizes silyl ethers to aldehydes in the presence of azobisisobutyronitrile. It is also used for the modification of ribosomal sulfhydryl groups.
Source of free-radical or positive bromine. For examples of radical benzylic bromination (Wohl-Ziegler), see: Org. Synth. Coll., 4, 921 (1963); 5, 145, 329, 825 (1973). The use of the ozone depleting solvent CCl4 has been avoided by the use of the ionic liquid 1-n-Butyl-3-methylimidazolium hexafluorophosphate, L19086 : Synlett, 702 (2003). Cleavage of carbohydrate benzyl ethers: J. Org. Chem., 55, 378 (1990), and of benzyl esters: Synlett, 219 (1994), occur under mild conditions; the benzyl group is converted to benzaldehyde. For allylic bromination, see e.g.: Org. Synth. Coll., 4, 108 (1963);.9, 112, 191 (1998) review: Chem. Rev., 43, 271 (1948).
For free-radical ɑ-bromination of a Boc glycine ester, see: Org. Synth. Coll., 9, 526 (1998).
Both aliphatic and aromatic aldehydes are converted to acyl bromides under free-radical conditions: Tetrahedron Lett., 3809 (1979); Synlett, 347 (1990); Tetrahedron Lett., 31, 7237 (1990).
In acetonitrile, NBS is a mild and regiospecific nuclear brominating agent for activated aromatics such as methoxybenzenes and naphthalenes: J. Org. Chem., 60, 5328 (1995). Deactivated aromatics, e.g. nitroarenes and benzotrifluorides, can be m-brominated under mild conditions in good yield with NBS in TFA, in the presence of H2SO4: Synlett, 1245 (1999).
In the presence of a phosphine or phosphite, converts alcohols to alkyl bromides with inversion: Tetrahedron Lett., 3937 (1973). For a review of this and related reactions, see: Org. React., 29, 1 (1983).
Alkenes undergo trans-addition reactions with NBS in combination with a nucleophile. For examples, see: Org. Synth. Coll., 6, 184, 560 (1988). With alcohols, bromohydrin ethers are formed. For use in the synthesis of cyclopropenone, see: Org. Synth. Coll., 6, 361 (1988):
In the presence of DBU in MeOH, amides rearrange to amines in good yields, providing a mild and efficient alternative to the classical Hofmann halogen/ caustic alkali conditions: J. Org. Chem., 62, 7495 (1997).
Examples of the use of NBS as a mild, selective oxidizing agent:
Sulfides to sulfoxides: J. Org. Chem., 37, 3976 (1968). Oximes to nitrile oxides: J. Org. Chem., 37, 436 (1968). Secondary alcohol in the presence of primary: Tetrahedron Lett., 2745 (1979). (In DMSO): Alkynes to ɑ-diketones: Can. J. Chem., 49, 1099 (1979).
(Free radical): Aldehydes to acyl bromides or amides: Tetrahedron Lett., 31, 7237 (1990). Benzyl silyl ethers to aldehydes: Synlett, 345 (1990). Aldehydes to esters: Synlett, 347 (1990).
For use as a mild catalyst in acetalization reactions, see Triethyl orthoformate, A13587 .
For a brief feature on uses in synthesis, see: Synlett, 498 (2006). See also 1,3-Dibromo-5,5-dimethylhydantoin, A15510 .
Guha, S.; Rajeshkumar, V.; Kotha, S. S.; Sekar, G. A Versatile and One-Pot Strategy to Synthesize alpha-Amino Ketones from Benzylic Secondary Alcohols Using N-Bromosuccinimide. Org. Lett. 2015, 17 (3), 406-409.
Wang, W. X.; Zhang, Q. Z.; Zhang, T. Q.; Li, Z. S.; Zhang, W.; Yu, W. N-Bromosuccinimide-Mediated Radical Cyclization of 3-Arylallyl Azides: Synthesis of 3-Substituted Quinolines. Adv. Synth. Catal. 2015, 357 (1), 221-226.
Gefahrenhinweise (EU): H302-H314-H318
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