Koshland’s reagent

Figure 7. Modifications of indole groups (a) HNBB or Koshland s reagent (b) photooxidation (c) 4-nitrophenylsulfenyl chloride.

One common way to modify tryptophan residues occurs through the addition of 2-hydroxy-5-nitrobenzyl bromide (HNB). Also known as Koshland s reagent (68), this compound first alkylates the 3-position of the ring and eventually leads to the formation of a product mixture through subsequent intramolecular cyclization pathways. Fig. 6c. This reagent exhibits good tryptophan selectivity, although some levels of... 

Hydroxy-5-nitrobenzyl bromide (Koshland s reagent) 8.0. Crystallise the bromide from benzene or benzene/ligroin. C6H6 and AcOH, and very soluble in ligroin. [Beilstein 6 H 367.]... 

Bromo-H-(2-hydroxy-5-nitrophenyl)acetamide, 9CI. 2-Bromo-2 -hydroxy-5 -nitroacetanilide. Koshland III reagent. Koshland s reagent III [3947-58-8]... 

Me ether [3913-23-3]. 2- Bromomethy[)- J-methoxy-4-nitrobenzene, 9CI. 2-Methoxy-5-nitrobenzyl bromide. 2-Bromomethyl-4-nitroanisole. MNBB. Koshland s reagent II... 

Casnati and coworkers (69, 70) found that y, y-dimethylallyl bromide reacts with N-acetyl-tryptamine similarly to the Koshland s reagent. Two compounds were isolated and their structure (125) and (126) were determined (70). 

Spande, T. F., M. Wilchek, and B. Witkop The Reaction of Derivatives of Tryptophan, Tryptamine, and Other Indoles with 2-Hydroxy-5-nitrobenzyl Bromide (Koshland s Reagent). J. Amer. Chem. Soc. 90, 3256-3258 (1968). 

---