Methanol → HCID 9914765, compound

Participants

Reaction Conditions

Reaction Steps

A 500 ml two-necked round-bottomed flask was loaded with 5.25 g of PMBzBoc-A lactam 15f (10.36 mmol) and 200 ml of THF. After cooling to 0° C., a solution of 2.17 g of LiOH×H2O (51.8 mmol) in 50 ml of H2O was added dropwise over a period of 20 min. 30 ml of MeOH were then added, the ice bath was removed and the reaction mixture was stirred at room temperature for 1 h. An ion-exchange resin (Amberlite IR-120, H+ form) was then added until a pH of 7 was reached. The resin was removed by filtration and the solution was concentrated under reduced pressure to a volume of 100 ml. 200 ml of H2O were then added and a pH of 2 was adjusted by addition of 1 M aqueous HCl. The solution was extracted with EtOAc (3×200 ml) and the combined organic extracts were dried over MgSO4, filtered and concentrated in vacuo. The resulting residue was dissolved in 25 ml of hot MeOH. The product was then precipitated by addition of 10 ml of H2O. The precipitate was filtered, washed with H2O and dried over P4O10 to afford 1.95 g of 16. It was possible to obtain a further 0.57 g from the mother solution and the wash solutions to afford a total yield of 46%.

Provenance & Evidence