Dimethyl Sulfoxide → 5-Formyl-2(S)-phthalimidopentanoic acid

Participants

Reaction Steps

6-Hydroxy-2(S)-phthalimidohexanoic acid (1.94 g) was dissolved in 145 ml of CH2Cl2 containing 2.26 ml of pyridine. Pyridinium dichromate (1.95 g) was added and the mixture stirred overnight under nitrogen. By addition to 200 ml of ethyl acetate and filtration, chromium salts were removed. The filtrate was concentrated under vacuum. The residue was redissolved in 250 ml of ethyl acetate and the solution refiltered. The filtrate was finally passed through a MgSO4 pad to remove trace amounts of chromium salts and concentrated to afford a white solid, 0.475 g; m.p. 219°-22°; [α]D25° =-41.6° (THF, c=1.5). Tlc on silica (4:1 ethyl acetate:acetic acid) indicated a single spot at Rf =0.79. 'H NMR spectrum (d6 -DMSO) showed triplets at δ9.65 (1H) and δ4.85 (1H, J=7.5 Hz), a singlet at δ7.95 (4H), and a broad multiplet at δ0.9-2.50 (6H) ppm. 13C NMR spectrum (d6 -DMSO) showed single absorptions at 202.9, 170.5, 167.5, 134.9, 131.3, 123.5, 51.7, 42.4, 27.8, and 18.7 ppm.

Provenance & Evidence