Dimethylformamide → Ninhydrin

Participants

Reaction Steps

A solution of N-α-Fmoc-N-im-trityl-L-histidine or N-α-Fmoc-O-t-butyl-L-serine (0.9282 g, 1.50 mmol) and HOBt monohydrate (0.2296 g, 1.50 mmol) in DMF/DCM (1:1) (10 ml) and DIC (0.1995 g, 1.58 mmol) was added to the deprotected resin. After 90 min., the peptide-resin was washed with DMF and DCM (both 4×12 mL×1 min.) and gave a negative Kaiser ninhydrin test. After removal of the Fmoc group as described, N-α-Fmoc-O-t-butyl-L-threonine (0.6006 g, 1.51 mmol) was coupled as described in the previous step, followed by removal of the Fmoc group. Coupling of N-α-Fmoc-α-methyl-2-fluoro-L-phenylalanine (0.4167 g, 0.993 mmol) was performed by mixing a solution of the amino acid and HOBt monohydrate (0.1529 g, 0.998 mmol) in DMF/DCM 1:1 (10 ml) and DIC (0.1260 g, 0.998 mmol) with the deprotected peptidyl-resin for 4 hours. After DMF and DCM (both 4×12 mL×1 min.) washes, a sample of the peptide-resin gave a negative Kaiser ninhydrin test. Performed steps 1 to 4 above to remove the Fmoc group.

Provenance & Evidence