O-Nitrophenylsulfenyl chloride

PEPTIDE SYNTHESIS Diphenylphosphoryl azide. N-Ethoxycarbonyl-2-ethoxy-l,3-di-hydroquinoline. o-Nitrophenylsulfenyl chloride. 2-Picolyl chloride hydrochloride. Silicon tetrachloride. Triphenylpbosphine. Triphcnylphosphinc-Carbon tetrachloride. Triphcnyl phosphite. 

Triethylamine or N-methylmorpholine added dropwise to an ice-cooled soln. of L-phenylalanine-N-carboxylic acid anhydride and o-nitrophenylsulfenyl chloride in dry ethyl acetate or tetrahydrofuran, and the product isolated after 0.5 hr. 

Various aromatic sulfenyl chlorides, e.g. phenylsulfenyl chloride , triphenylmethylsulfenyl chloride and o-nitrophenylsulfenyl chloride , react with amines to yield the corresponding sulfenyl derivatives (reaction 13). The acylation is carried out under neutral... 

The 2,4,6-trimethylbenzyl ester has been prepared from an amino acid and the benzyl chloride (Et3N, DMF, 25°, 12 h, 60-80% yield) it is cleaved by acidic hydrolysis (CF COOH, 25°, 60 min, 60-90% yield 2 N HBr/HOAc, 25°, 60 min, 80-95% yield) and by hydrogenolysis. It is stable to methanolic hydrogen chloride used to remove A-o-nitrophenylsulfenyl groups or triphenylmethyl esters. ... 

Introduction of the o-nitrophenylsulfenyl group is simple using commercially available 2-nitrobenzenesulfenyl chloride (mp 74-76 C) and aqueous base... 

Protection of thiols.1 The f-butyl group has been of limited service for protection of thiols because removal has involved rather drastic treatment with liquid HF. /-Butyl thioethers can be cleaved by treatment with o-nitrobenzene-sulfenyl chloride in acetic acid at 25° to give S-o-nitrophenylsulfenyl derivatives. These products are reduced to thiols with NaBH4, HSCH2C02H, or HOCH2CH2SH. 

Trifluoromethanesulfonic acid in the presence of anisole cleaves at room temp, a number of protecting groups used in peptide chemistry without significant side reactions. - E N-(o-Nitrophenylsulfenyl)valine allowed to react 3-5 min. in methylene chloride with 5-10 equivalents trifluoromethanesulfonic acid and 1.5-3 equivalents anisole as scavenger valine. Y 99.9%. F. e., also in tri-fluoroacetic acid instead of methylene chloride, s. H. Yajima et al., Chem. Com-mun. 1974, 107. 

The pyrrolidine enamine of cyclohexanone (28) has been shown to react with 0-, m-, and p-nitrobenzenesulfenyl chlorides (105). A mixture of the 2-mono- and 2,6-bis(o-, m-, and p-nitrophenylsulfenyl)cyclohexanones is obtained on hydrolysis. Only the monosubstituted derivative (155) is... 

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