Efficiency in Peptide Coupling: 1-Hydroxy-7-azabenzotriazole vs 3,4

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J. Org. Chem. 1995,60, 3561-3564

Efficiency in Peptide Coupling: 1-Hydroxy-7-azabenzotriazoleus 3,4-Dihydro-3-hydroxy-4-0~01,2,3-benzotriazine+ Louis A. Carpino* and Ayman El-Faham* Department of Chemistry, Box 34510, University of Massachusetts, Amherst, Massachusetts 01003-4510

3561

Table 1. Effect of Solvent and Additive on the Preservation of Configuration during Formation of Z-Phg-h.o-NH2via Carbodiimide Coupling@ coupling reagent

solvent

EDC/HOAt (DCCT EDC/HOAt (DCCF EDC/HODhbt (DCCT EDCMODhbt (DCCT EDC/HOBt (DCCT EDC/HOBt (DCCT

DMF TFE/TCM

a

DMF TFE/TCM DMF TFE/TCM

yield, %

DL, %

81.4 (83.0) 7.0 (3.3) 50.1 (71.3)