Table 1.

Threonine extension by coupling and subsequent free-radical desulfurization

Entry	Peptide	Coupling Product/Yield/Time	Desulfurization Product/Yield/Time
1			FmocRNEDLSGAT—OMe 9 / 92 % / 2 h
2			FmocRLGDSTAGQT—OMe 12 / 81% / 2 h
3			FmocRLGDSTAGYT—OMe 15 / 89% / 2 h
4			FmocRLGDSTAGWT—OMe 18 / 90% / 2 h
5			FmocRTGDSAGTT—OMe 21 / 84% / 2 h
6			FmocRLGDSTAGLT—OMe 24 / 80% / 2 h
7			FmocKYDSRGFT—OMe 27 / 80% / 2 h
8			FmocRTGDSAGVT—OMe 30 / 95% / 2 h
9			FmocRTGDSAGIT—OMe 33 / 82% / 2 h
10			FmocVRSYTAGPT—OMe 36 / 83% / 2 h

Key: (a) buffer at pH 6.5 (6.0 M Gn·HCl, 188.8 mM Na₂HPO₄), TCEP, rt (b) TCEP, VA-044, tBuSH, 37 °C. VA-044=2,2′-azobis-[2-(2-imidazolini-2-yl)propane] dihydrochloride.

TCEP=tris(2-carboxyethyl)phosphine.