4-Toluenesulfonyl chloride → (2S,4R)-4-(4-Methoxy-benzylsulfanyl)-1-(naphthalene-2-sulfonyl)-pyrrolidine-2-carboxylic acid N'-isobutyl-N'-(4-methyl-benzenesulfonyl)-hydrazide

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Reaction Steps

(step 3) 4.3 g (3.15 mmol) (2S,4R)-4-(4-Methoxy-benzylsulfanyl)-1-(naphthalene-2-sulfonyl)-pyrrolidine-2-carboxylic acid N′-isobutyl-hydrazide in 450 ml CH2Cl2 were treated with 5.6 ml (32.6 mmol, 4 eq) N-ethyldiisopropylamine, 3.1 g (16.3 mmol, 2 eq) p-toluene sulfonyl chloride and 100 mg (0.8 mmol, 0.1 eq) DMAP at 0° C. and was stirred at RT over night. 2.05 g (16.1 mmol, 2 eq) MeNHCH2CO2K were added and, the solution was stirred at RT for 1 h, 1M KHSO4 solution was added and, the phases were separated. The organic layer was extracted with sat. NaHCO3 and, the inorganic layers were washed with CH2Cl2. The combined organic phases were washed with brine, dried over Na2SO4 and evaporated. Purification of the crude residue by flash chromatography with hexane:ethyl acetate 2:1 as eluent yields 2.68 g (48%) (2S,4R)-4-(4-Methoxy-benzylsulfanyl)-1-(naphthalene-2-sulfonyl)-pyrrolidine-2-carboxylic acid N′-isobutyl-N′-(4-methyl-benzenesulfonyl)-hydrazide, which was directly subjected to the following reaction.

Provenance & Evidence