Methyl N-(triethylammoniosulfonyl)carbamate → Ethyl (4S)-2-{(1R)-1-[2-(tert-butoxy)-2-oxoethyl]4-cyclohexylbutyl}-4,5-dihydro-1,3-oxazole-4-carboxylate

Participants

Reaction Steps

A solution of tert-butyl(3R)-6-cyclohexyl-3-({[(1S)-2-ethoxy-1-(hydroxymethyl)-2-oxoethyl]amino}carbonyl)hexanoate (preparation 151) (10.09, 24.2 mmol) in THF (80 ml) was treated with Burgess reagent (6.34 g, 26.6 mmol) and heated at reflux for 1 hour. The reaction mixture was allowed to cool to room temperature and stored in a fridge for 3 days. The solvent was removed under reduced pressure. The crude material was ourififed on a silica column eluting with a solvent gradient of pentane:EtOAc (100:0) gradually changing to (80:20) to afford the title compound as a colourless oil (9.26 g, 97%).

Provenance & Evidence