Trifluoroacetic acid → 2-[2,4-Bis(benzyloxy)phenyl]acetic Acid

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Reaction Steps

The above obtained crude 2,4-dibenzyloxyphenylacetyl chloride [X] was dissolved in anhydrous N,N-dimethylformamide (20 ml) and then thereto was added a solution of L-asparagine p-nitrophenyl ester trifluoroacetate in anhydrous N,N-dimethylformamide [prepared by treating N-(p-methoxybenzyloxycarbonyl)-L-asparagine p-nitrophenyl ester (1.6 g) with trifluoroacetic acid (3 ml) in the presence of anisole (1.2 g) at 0° C. for 1 hour, concentrating the treated product to dryness under reduced pressure and dissolving the residue in anhydrous N,N-dimethylformamide (20 ml)]. Thereto was further added triethylamine (1.8 ml), followed by concentrating under reduced pressure at 40° C. or lower. The residue was subjected to separation and purification by a silica gel column (inner diameter: 5 cm, length: 30 cm; developer: ethyl acetate) to obtain 2,4-dibenzyloxyphenylacetyl-L-asparagine p-nitrophenyl ester [IIa-1] (290 mg, yield from [IX] 13%).

Provenance & Evidence