Morpholine → (3R,6R)-3-(2,3-Dihydro-1H-inden-2-yl)-1-((1R)-1-(2,6-dimethyl-3-pyridinyl)-2-(4-morpholinyl)-2-oxoethyl)-6-((1S)-1-methylpropyl)-2,5-piperazinedione

Participants

Reaction Steps

A suspension of {(3R,6R)-3-(2,3-dihydro-1H-inden-2-yl)-6-[(1S)-1-methylpropyl]-2,5-dioxo-1-piperazinyl}(2,6-dimethyl-3-pyridinyl)acetic acid hydrochloride (5.0 g, 10.3 mmol) (intermediate 5) in dry dichloromethane (50 ml) was treated with 1,1-carbonyldiimidazole (2.6 g, 16 mmol) and the reaction mixture was stirred under nitrogen for 18 hours. Morpholine (4.8 ml, 55 mmol) was added and the resultant solution was left to stand under nitrogen for 18 hours. The solvent was removed in vacuo and the residue was separated between ethyl acetate and water. The organic phase was washed with brine and dried over anhydrous magnesium sulphate. The solvent was removed in vacuo and the residue was dissolved in dichloromethane. This was applied to a basic alumina cartridge (240 g) and eluted using a gradient of 0-7.5% methanol in diethyl ether (9CV), 7.5-10% methanol in diethyl ether (1CV) and 10% methanol in diethyl ether (1CV). The required fractions were combined and evaporated in vacuo to give (3R,6R)-3-(2,3-dihydro-1H-inden-2-yl)-1-[(1R)-1-(2,6-dimethyl-3-pyridinyl)-2-(4-morpholinyl)-2-oxoethyl]-6-[(1S)-1-methylpropyl]-2,5-piperazinedione as a white solid (2.4 g, 45%).

Provenance & Evidence