Triphenylphosphine → (4-amino-1-{4-[(methylsulfonyl)amino]butyl}-1H-imidazo[4,5-c]quinolin-2-yl)methyl N-[(benzyloxy)carbonyl]-L-valinate

Participants

Reaction Steps

To a stirred suspension of N-[4-(4-amino-2-hydroxymethyl-1H-imidazo[4,5-c]quinolin-1-yl)butyl]methanesulfonamide (2.1 g, 5.8 mmol) in THF was added triphenylphosphine (1.5 equivalents, 8.7 mmol, 2.2 g) followed by CBZ-L-valine (1.5 equivalents, 8.7 mmol, 2.3 g). The suspension was stirred for 5 min after which it was cooled in an ice-bath. To this cooled reaction mixture diisopropyl azodicarboxylate (DIAD, 1.8 equivalents, 10.4 mmol, 2.0 mL) was added and the reaction was warmed to room temperature and stirred overnight. The solvent was evaporated under reduced pressure and the crude solid was purified by prep HPLC (ISCO Combiflash Separation System, Biotage Si 40+M column, eluted with a gradient of 0-8% methanol in dichloromethane with 1% ammonium hydroxide) to provide a solid. The solid was heated in diethyl ether and filtered to afford (4-amino-1-{4-[(methylsulfonyl)amino]butyl}-1H-imidazo[4,5-c]quinolin-2-yl)methyl N-[(benzyloxy)carbonyl]-L-valinate (2 g) as a beige solid, mp 99-100° C.; MS (ESI) m/z 597 (M+H)+; Anal. Calcd for C29H36N6O6S: C, 58.37; H, 6.08; N, 14.08. Found C, 57.98; H, 6.31; N, 13.82.

Provenance & Evidence