Diisopropylethylamine → (2S,3S)-1-(3-Chloro-4-cyano-2-methylphenylcarbamoyl)-3-hydroxy-pyrrolidine-2-carboxylic acid methyl ester

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Reaction Conditions

Reaction Steps

A solution of ester 1A (500 mg, 2.75 mmol) in dry CH2Cl2 (10 mL) was cooled to 0° C., treated with Hunig's base (0.53 mL, 3.04 mmol) and stirred at 0° C. for 30 min. The solution was treated with isocyanate 23E (505 mg, 2.62 mmol), and the resulting suspension was stirred at rt for 3 h. The insoluble solids were filtered off and the filtrate was partitioned between aqueous NH4Cl (6.0 mL) and CH2Cl2 (3×60 mL). The combined organic phases were washed with brine, dried (Na2SO4), filtered and concentrated under reduced pressure. The residue and insoluble solids were combined and chromatographed (silica gel; EtOAc/hexane gradient) to yield the title compound (177.2 mg, 75.3%) as a white solid, mp 189-191° C. HPLC: 1.72 min (retention time) (Conditions: YMC S-5 C-18 (4.6×50 mm), eluting with 0-100% B, 4 min gradient. (A=90% H2O-10% CH3CN-0.1% TFA and B=10% H2O-90% CH3CN-0.1% TFA); Flow rate at 4 mL/min. UV detection at 220 nm). Chiral HPLC: retention time=22.2 min (100%); Conditions: AD (4.6×250 mm); Eluted with 20% isopropanol in heptane for 30 min at 1 mL/min. MS (ES) m/z 338 [M+H]+.

Provenance & Evidence