Cesium carbonate → benzyl (S)-1-((1S,2S,4R)-4-hydroxy-2-isopropylcyclohexyl)-2-oxopyrrolidin-3-ylcarbamate

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Reaction Steps

Benzyl (S)-1-((1S,2S,4R)-4-(tert-butyldimethylsilyloxy)-2-isopropylcyclohexylamino)-4-(methylthio)-1-oxobutan-2-ylcarbamate (5.3 g) was dissolved in iodomethane (90 mL), and the resulting solution was stirred at rt for 72 h before being concentrated in vacuo. The residue was dissolved in methylene chloride, and the resulting solution was concentrated; this was repeated to afford the salt. MS found: (M+H)+=586.5. This material was dissolved in DMSO (30 mL) and the solution was charged with Cs2CO3 (12.7 g). After 6 h, the reaction was partitioned between EtOAc and brine. The organic phase was dried (MgSO4), filtered, and concentrated in vacuo. The residue was purified by flash chromatography to afford benzyl (S)-1-((1S,2S,4R)-4-hydroxy-2-isopropylcyclohexyl)-2-oxopyrrolidin-3-ylcarbamate [580 mg; MS found: (M+H)+=375.3] and benzyl (S)-1-((1S,2S,4R)-4-(tert-butyldimethylsilyloxy)-2-isopropylcyclohexyl)-2-oxopyrrolidin-3-ylcarbamate [1.0 g; MS found: (M+H)+=489.4].

Provenance & Evidence