N-Hydroxysuccinimide trifluoroacetate

Peptide synthesis /-Amyl chloroformate. Bis-(2,4-dinitrophenyl)carbonate. Bis-o-phenylene pyrophosphite. i-Butyl chloroformate. sec-Butyl chloroformate. /-Butyl chloroformate. /-Butyl 2,4,5-trichlorophenyl carbonate. CopoIy(ethylene-N-hydroxymaleimide). N,N-Diethyl-I-propynylamine. Di-(p-nitrophenyl)sulfate. Ethoxyacetylene. N-Ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline. N-Ethylbenzisoxazolium fluoroborate. Ethyl chloroformate. N-Ethyl-5-phenylisoxazolium-3 -sulfonate. N-Hydroxysuccinimide trifluoroacetate. Methyl-morpholine. 4-Methylthiophenol. p-Nitrophenol. Oxalylchloride. Pentachlorophenol. Pentamethylbenzyl chloride. /-Pentyl chloroformate. Phenacyl bromide. Polyhexamethylene carbodiimide. Tetraethyl pyrophosphite. 1,2,4-Triazole. 

N-Hydroxysuccinimide trifluoroacetate, 2, 219. Mol. wt. 211.10. Pierce Chemical Co. supplies the reagent as white crystals melting at 70-72°. The material is extremely hygroscopic but is stable when protected from moisture. 

Treatment of N hydroxysuccinimide with trifluoroacetic anhydnde gives N trifluoroacetoxysuccinimide quantitatively [27] Some otherwise hardly accessible trifluoroacetylated tertiary alcohols are readily prepared, though in poor yields, by reacting the appropriate anhydride with an excess of an organometallic reagent [22] (equation 11)... 

Scheme S Semisynthetic method for the cleavage of phospholipase A2 and the reconstitution of azobenzene-modified phospholipase A2. Acm = acetamide, Amd = s-amidinated, DCC = dicyclohexylcarboxiimide, HOSu = N-hydroxysuccinimide, TFA = trifluoroacetic acid, Xaa = trans-azobenzene phenylalanine.

Abbreviations used Dde, N-[l-(4,4-dimethyl-2,6-dioxocyclohexadiene)]-ethyl DIEA, diisopropylethylamine DMF, N,N-dimethylformamide EDC, l-Ethyl-3-(3 -dimethylaminopropyl)carbodiimide hydrochloride HOBt, 1-hydroxybenzotriazole NHS, N-hydroxysuccinimide NMP, l-methyl-2-pyrroIidinone PAL, Peptide Amide Linker [5-(4-(9-fluorenylmethyloxycarbonyl) aminomethyl-3,5-dimethoxyphenoxy) valeric acid] PyBOP, Benzotriazole-l-yl-oxy-trispyrrolidino-phosphonium hexafluorophosphate TFA, trifluoroacetic acid. 

Sample preparation Take up 1.5 mg levothyroxine in 200 p.L 100 mM sodium bicarbonate and 400 j,L reagent, stir in an ice bath for 30 min, evaporate to dr3mess below 30°, add 100 (jlL trifluoroacetic acid to the dry residue, let stand for 30 min at room temperature, add 2 mL 1 M sodium hicarhonate, centrifuge. Remove the precipitate and dissolve it in 600 p-L MeOH 20 mM NaOH 50 50, inject a 15 p-L aliquot. Reagent was 7 mg/mL BOC-L-Leu-SU (tert-butyloxy-L-leudne-N-hydroxysuccinimide ester) in MeOH, prepared immediately before use.)... 

Fig. 6. Outline of the synthesis of glucagon by the solution procedure. DCCI, dicyclo-hexylcarbodiimide HOSU, N-hydroxysuccinimide NPS, 2-nitrophenylsulfenyl tBu, t-butyl AdOC, adamantyloxycarbonyl TFA, trifluoroacetic acid...

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