Tributylstannane → t-Butyl 4-[9-(benzoylamino)-6,10-dioxo-1,2,3,4,7,8,9,10-octahydro-6H-pyridazino-[1,2-a][1,2]diazepine-1-carboxamido]-5-oxopentanoate semicarbazone

Participants

Reaction Conditions

Reaction Steps

A solution of (1S,9S) 6,10-dioxo-1,2,3,4,7,8,9,10-octahydro-9-(benzoylamino)-6H-pyridazino[1,2-a][1,2]diazepine-1-carboxylic acid (212e) (345 mg, 1.0 mmol), (4S) t-butyl N-(allyloxycarbonyl)-4-amino-5-oxopentanoate semicarbazone (208a) (361 mg, 1.1 mmol, 1.1 equiv) and (Ph3P)2PdCl2 (20 mg) in CH2Cl2 (5 ml), was treated dropwise with n-Bu3SnH (0.621 ml, 2.3 mmol, 2.1 equiv). The resulting orange brown solution was stirred at 25° C. for 10 min and then 1-hydroxybenzotriazole (297 mg, 2.2 mmol, 2 equiv) was added. The mixture was cooled to 0° C. and ethyldimethylaminopropyl carbodiimide (253 mg, 1.3 mmol, 1.2 equiv) added. After stirring at 0° C. for 10 min and then at room temperature overnight, the mixture was diluted with EtOAc (50 ml) and the resulting solution washed successively with 1M HCl (3×25 ml), 10% NaHCO3 (3×25 ml) and sat. aq. NaCl, dried (MgSO4) and concentrated. Flash chromatography on silica gel (2-10% methanol in CH2Cl2) afforded compound 233e (280 mg, 49%) as a tan solid: [α]D20 −95 (c 0.09, MeOH); IR (KBr) 3477, 3333, 2968, 2932, 1633, 1580, 1535, 1423, 1378, 1335, 1259, 1156, 1085, 709; 1H NMR (CDCl3) δ 9.32 (1H, s), 7.83-7.39 (6H, m), 7.11-7.09 (1H, m), 6.30-5.30 (2H, brs), 5.17-5.05 (2H, m), 4.62-4.38 (2H, m), 3.30-3.15 (1H, m), 3.13-2.65 (2H, m), 2.46-2.19 (3H, m), 2.15-1.54 (8H, m), 1.42 (9H, s).

Provenance & Evidence