Diisopropylcarbodiimide → Cypate Bombesin

Participants

Reaction Steps

The resin-bound bombesin analog, i.e. Fmoc-Gln(Trt)-Trp(Boc)-Val-Ala-Gly-His(Trt)-Leu-Met-Lys(Boc)-Rink-Amide resin was assembled from Rink amide-resin (50 mg, 0.031 mmol) based on the conventional Fmoc chemistry. After the N-terminal Fmoc was removed by piperidine in DMF (20%), a solution of Cypate (211.5 mg, 0.3 mmol), HOBT (40.5 mg, 0.30 mmol), DIC (126.0 mg, 0.1 mmol) was added. The resulting mixture was swirled overnight at room temperature. The resin was washed with DMF and DCM, cleaved with a TFA solution (TFA:Phenol:thioanisole:water v:v 85:5:5:5, 4 ml) (2 h), and concentrated. The product was precipitated in cooled tert-butyl methyl ether to afford 2.8 mg of the crude intermediate 16.

Provenance & Evidence