1,1'-(9,9-Dimethyl-9H-xanthene-4,5-diyl)bis(1,1-diphenylphosphine) → (R)-t-butyl 2-((t-butyldimethylsilyloxy)methyl)-4-(6-chloropyridin-3-yl)piperazine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

Compound 308 (361 mg, 1091 μmol), 5-bromo-2-chloropyridine (200 mg, 1039 μmol), Tris(dibenzylideneacetone)dipalladium (0) (71.4 mg, 77.9 μmol), 4,5-bis(diphenylphosphino)-9,9-dimethyl-9H-xanthene (90.2 mg, 156 μmol), and sodium t-butoxide (200 mg, 2079 μmol) were taken up in toluene (5 mL). The reaction was purged with argon and heated at 80° C. for 5 hours. The resulting solution was added to aqueous K2CO3 (10%, 30 mL) and extracted with dichloromethane+10% methanol (3×30 mL). The combined organics were dried (MgSO4) and evaporated to give an orange tar. Silica gel chromatography (gradient elution hexanes/0-20% ethyl acetate) afforded compound 309 as a pale yellow oil (219 mg, 48%).

Provenance & Evidence