Dicyclohexylcarbodiimide → Deacetylvinblastine 3-aminopropylamide norleucine amide

Participants

Reaction Steps

To a DMF solution (1 ml) of Boc-Nle (22 mg, 0.095 mmol) was added 318 μl of a 1M solution of HOBT (in NMP) followed by 280 μl of a 1M solution of DCC (in NMP). After 30 min., intermediate (11) (0.0624 mmol) was added in a 3.5 ml DMF. The pH of the reaction was adjusted ~7.5 with diisopropylethylamine. After stirring for 18 hrs the reaction was concentrated to an oil and the Boc protecting group removed by treating the oil with a 1:1 solution of TFA: CH2Cl2 (20 ml). After 5 min. the reaction was concentrated to dryness. Purification was achieved by preparative HPLC on a C-18 reverse phase support (Waters, Delta Pak). Buffer A=0.1% TFA-H2O; B=0.1% TFA-CH3CN. The crude product was loaded in 100% A buffer (100 ml) and a step gradient of 100% A to 30% A was used at a flow rate of 75 ml/min. Homogeneous product fractions were pooled and freeze-dried to yield (12).

Provenance & Evidence