3-Bromopyridine → tert-butyl (3R)-3-methyl-4-pyridin-3-ylpiperazine-1-carboxylate

참여 물질

반응 조건

반응 단계

_Repeat of reaction EN05798-78_ Diacetoxypalladium (0.112 g, 0.50 mmol) and dicyclohexyl(2',6'-diisopropoxybiphenyl-2-yl)phosphine (0.466 g, 1.00 mmol) were dissolved in toluene (15 mL) at ambient temperature under nitrogen. The mixture was degassed and purged with nitrogen several times and heated to 50°C for 20 mins. In a separate vessel, were mixed 3-bromopyridine (0.789 g, 4.99 mmol), sodium 2-methylpropan-2-olate (0.720 g, 7.49 mmol), (R)-tert-butyl 3-methylpiperazine-1-carboxylate (1g, 4.99 mmol) and toluene (10 mL). The mixture was degassed and purged with nitrogen several times. The catalyst mixture was added to the reaction vessel and the resulting mixture was degassed and purged with nitrogen, and heated at 100 °C under nitrogen overnight. The reaction mixture was filtered through celite, washing with EtOAc/MeOH. The filtrate was concentrated and the residue purified by flash silica chromatography, elution gradient 20 to 100% EtOAc in heptane. Pure fractions were evaporated to dryness to afford (R)-tert-butyl 3-methyl-4-(pyridin-3-yl)piperazine-1-carboxylate (1.426 g, 103 %) as a pale orange gum. [Rf ~ 0.1 in 1:1 EtOAc/hept] Note: Trace Ruphos contaminating product

출처 및 근거