Pyridine → (S)-4-[2-(3-Fluoro-2-methyl-benzyl)-1-phenyl-indolizine-3-carbonyl]-2-methoxycarbonylmethyl-piperazine-1-carboxylic acid tert-butyl ester

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Reaction Steps

To a solution of the compound of example 1, step 3 (1.32 g, 4.19 mmol) in 20 ml of DCM at 0° C. were added pyridine (0.34 ml, 4.19 mmol) and then a 20% solution of phosgene in toluene (2.20 ml, 4.19 mmol). The mixture was stirred at room temperature for 1.5 h and then added dropwise to an ice-cooled (0° C.) solution of the compound of step 3 (1.189 g, 4.60 mmol) and triethylamine (0.58 ml, 4.60 mmol) in 32 ml of DCM. The mixture was stirred at room temperature overnight, then diluted with 30 ml of DCM and washed twice with 1 N hydrochloric acid, twice with a saturated sodium hydrogencarbonate solution and twice with brine. The organic phase was dried over sodium sulfate, filtered and evaporated to dryness under reduced pressure. The residue was purified by chromatography on silica gel (cyclohexane/EA, 80:20, then 70:30) to give 1.44 g of the title compound as a pale yellow-green powder.

Provenance & Evidence