Water → HCID 12811391, compound

Participants

Reaction Steps

Dissolve 1-benzyloxycarbonyl-4-keto-(S)-proline (15.7 g, 60 mmol) in acetic acid (45 ml) and ethyl acetate (45 ml), add 1,2-ethanedithiol (6.2 g, 66 mmol) and stir under nitrogen. Add boron trifluoride etherate (redistilled) and stir 4 hours. Pour the reaction mixture into a mixture of water (175 ml) ethyl acetate (120 ml) and ether (60 ml). Wash the organic layer with water (3×175 ml) then extract twice with 1.0 N sodium bicarbonate (150 ml, then 50 ml). Acidify the aqueous layer to pH 1 with concentrated hydrochloric acid, extract twice with ether (150 ml, then 50 ml). Wash the organic layer with brine, dry over anhydrous magnesium sulfate and concentrate in vacuo to obtain crude 7-benzyloxycarbonyl-1,4-dithia-7-azaspiro[4.4]nonane-8(S)-carboxylic acid as an oil (16.1 g).

Provenance & Evidence