Diisopropylethylamine → Allyl O-({(3S)-4-{[(2R)-1-amino-1-oxo-3-(tritylsulfanyl)propan-2-yl]amino}-3-[(tert-butoxycarbonyl)amino]-4-oxobutyl}carbamoyl)-N-(tert-butoxycarbonyl)-L-tyrosinate

Participants

Reaction Conditions

Reaction Steps

2.50 g (4.42 mmol) of the compound from example 2A was dissolved in 100 ml dichloromethane. 1.602 g (4.42 mmol) S-Trityl-L-cysteinamide, 0.77 ml (4.42 mmol) N,N-diisopropylethylamine and 1.68 g (4.42 mmol) HATU were added. The reaction mixture was split into 5 portions. The portions were heated for 30 min in a sealed tube at 60° C. in a microwave synthesizer. From the combined reaction mixture the solvent was removed by rotary evaporation (approx. 40° C., approx. 200 mbar, approx. 30 min.). The raw product was dissolved in dichloromethane and chromatographed over approx. 600 ml silica gel. Solvents used were dichloromethane/ethyl acetate 2/1, dichloromethane/ethyl acetate 1/1, dichloromethane/methanol 20/1 and dichloromethane/methanol 10/1. The product-containing fractions were combined and concentrated to dryness under reduced pressure. This gave 4.12 g (3.30 mmol, 75% of theory, 73% purity) of the desired product.

Provenance & Evidence