N-Bromosuccinimide-Dimethyl Sulfide1

(NBS)

[128-08-5]  · C4H4BrNO2  · N-Bromosuccinimide-Dimethyl Sulfide  · (MW 177.99) (DMS)

[75-18-3]  · C2H6S  · N-Bromosuccinimide-Dimethyl Sulfide  · (MW 62.13)

(converts allylic and benzylic alcohols to bromides under neutral conditions;1 slowly converts primary alcohols to bromides;1 oxidizes primary and secondary alcohols to aldehydes or ketones2)

Alternate Name: NBS-DMS.

Physical Data: reagent is formed in situ. See entries for N-Bromosuccinimide and Dimethyl Sulfide.

Solubility: sol methylene chloride, carbon tetrachloride, toluene.

Preparative Method: freshly prepared by dissolving N-bromosuccinimide (5.4 g, 30 mmol) in methylene chloride (100 mL) at 0 °C under argon and slowly adding excess dimethyl sulfide (2.23 g, 36 mmol). Stir the resultant yellow slurry for 1 h at 0 °C before use.3 Oxidation and bromide replacement reactions are typically carried out between -25 and 0 °C in methylene chloride.

Handling, Storage, and Precautions: use protective clothing; use in a fume hood.

Conversion of Alcohols to Bromides.

The principal use for NBS-DMS is to convert allylic and benzylic alcohols to allylic and benzylic bromides (see N-Chlorosuccinimide-Dimethyl Sulfide (NCS-DMS)). Eqs 1-31,3,4 illustrate typical replacements of the hydroxy group of a primary allylic alcohol without rearrangement. This reaction is a much milder way of introducing bromide than the standard Phosphorus(III) Bromide reaction, which is incompatible with acid-sensitive functionalities because it generates HBr. In some cases, secondary allylic alcohols (eqs 4 and 5) tend to undergo an SN2 displacement of the allylic alcohol and rearrange to the primary allylic bromides. In these examples5,6 bearing a sulfoxide or sulfone, the rearrangements proceed with high (E) selectivity.

NBS-DMS is also a mild and practical reagent for synthesizing benzylic bromides from benzylic alcohols. As in the case of allylic alcohols, it is superior to PBr3 when sensitive functionality is involved because no HBr is produced. Reactions of NBS-DMS proceed rapidly in high yield and high purity (eq 6).7

NBS-DMS is also capable of converting alkyl alcohols to bromides in reasonable yields. Eq 7 shows an example of this type of conversion that occurs at 20 °C in 36 h1 (see also Carbon Tetrabromide and Triphenylphosphine Dibromide).

Oxidation of Primary and Secondary Alcohols.

Oxidations using NBS-DMS are part of a larger family of sulfonium ion-type oxidations (see also Dimethyl Sulfoxide-Oxalyl Chloride and Dimethyl Sulfide-Chlorine), and are carried out in a similar manner to the NCS-DMS oxidation.8 The reactions take place in 2 h at temperatures between 0 °C and -78 °C. The sulfoxonium ion intermediate is decomposed with Triethylamine to generate the carbonyl compound (eqs 8 and 9), as with NCS-DMS. This reagent is not useful for oxidizing allylic or benzylic alcohols because of the bromide replacement reaction described above.2


1. Corey, E. J.; Kim, C. U.; Takeda, M. TL 1972, 4339.
2. Kim, K. S.; Baik, W. P.; Hahn, C. S. Bull. Korean Chem. Soc. 1984, 5, 204.
3. Bhatnagar, S. C.; Caruso, A. J.; Polonsky, J. T 1987, 43, 3471.
4. Murphy, J. A.; Patterson, C. W. JCS(P1) 1993, 405.
5. Auvray, P.; Knochel, P.; Normant, J. F. T 1988, 44, 6095.
6. Bonfand, E.; Gosselin, P.; Maignan, C. TA 1993, 4, 1667.
7. Gervais, C.; Anker, D.; Chareire, M.; Pacheco, H. BSF(2) 1979, 241.
8. Corey, E. J.; Kim, C. U. JACS 1972, 94, 7586.

William V. Murray

The R. W. Johnson Pharmaceutical Research Institute, Raritan, NJ, USA



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