Dimethylformamide dimethyl acetal → {1-Benzyl-3-[(3-dimethylaminomethylene-2-oxo-2,3-dihydro-1H-indole-5-sulfonyl)-isobutyl-amino]-2-hydroxy-propyl}-carbamic acid hexahydro-furo[2,3-b]furan-3-yl ester

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Reaction Steps

A solution of {1-benzyl-2-hydroxy-3-[isobutyl-(2-oxo-2,3-dihydro-1H-indole-5-sulfonyl)-amino]-propyl}-carbamic acid hexahydro-furo[2,3-b]furan-3-yl ester 20 (59 mg, 0.1 mmol) and N,N-dimethylformamide dimethylacetal (27 ul, 0.2 mmol) in 1 ml of chloroform was refluxed for 1 h, cooled, and concentrated in vacuo. The residue was chromatographed on silica gel, (methanol:ethyl acetate 3:97) to obtain {1-benzyl-3-[(3-dimethylaminomethylene-2-oxo-2,3-dihydro-1H-indole-5-sulfonyl)-isobutyl-amino]-2-hydroxy-propyl}-carbamic acid hexahydro-furo[2,3-b]furan-3-yl ester 21 (48 mg, 75%). TLC: Rf 0.09 (ethyl acetate). MS m/z 643 (MH)+. 1H NMR (CDCl3) consistent with structure.

Provenance & Evidence