Dimethylamine → (r)-5-Biphenyl-4-ylmethyl-3-[1-diisopropylamino-meth-(e)-ylidene]-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

351 mg (S)-2-Biphenyl-4-ylmethyl-5-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (8-a, R1=Boc) (1 eq, 1 mmol) and lithium hexafluorophosphate (1 eq) is added to tetrahydrofuran (10 ml). N,N-Dimethylformamide di-tert-butyl acetal (15, R6=Me, R7=Me, R8=tBu) (3 eq) and dimethylamine (0.5 eq) are added to the mixture. The mixture is stirred at room temperature for 3 h. The volatiles are removed under reduced pressure. Ethyl acetate (20 ml) is then added. The mixture is washed with saturated sodium carbonate solution (2×20 ml) and then with brine (20 ml). The organic layer is dried (Na2SO4) and concentrated under reduced pressure to afford (R)-5-biphenyl-4-ylmethyl-3-[1-dimethylaminometh-(E/Z)-ylidene]-2-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (7-a, R1=Boc, R6=Me, R7=Me) or a salt thereof. The solutions are analysed by TLC (50% ethyl acetate in hexane). RF 0.21 (salt of 7-a, R1=Boc, R6=Me, R7=Me); RF 0.27 (7-a, R1=Boc, R6=Me, R7=Me); RF 0.68 (8-a, R1=Boc).

Provenance & Evidence