tert-butyl(2S)-2-[4-(hydroxymethyl)-2-oxo-1-pyrrolidinyl]butanoate → 1-[(1S)-1-(tertbutoxycarbonyl)propyl]-5-oxo-3-pyrrolidinecaboxaldehyde

Participants

Reaction Steps

In a three necked flask, under argon, a solution of tert-butyl(2S)-2-[4-(hydroxymethyl)-2-oxo-1-pyrrolidinyl]butanoate 398 (4.0 g, 0.016 mol.) in CH2Cl2 (8 ml) is added to a suspension of CrO3 (6.2 g, 0.062 mol.) in pyridine (111.3 ml)/CH2Cl2 (80 ml) stirred at room temperature. The temperature increases to 30° C. and the suspension is stirred for 0.2 h. The suspension is filtered through celite and the filtrate is washed successively with HCl 1N, brine, dried over magnesium sulfate and concentrated in vacuo to afford the crude aldehyde which is purified by column chromatography on silicagel (hexane/acetone 70/30 (v/v)) to afford 2.03 g of 1-[(1S)-1-(tertbutoxycarbonyl)propyl]-5-oxo-3-pyrrolidinecarboxaldehyde 396 (41%). Alternatively, the reaction can also be conducted with racemic ester to afford the racemic aldehyde with a similar yield. Analysis of a 1/1 mixture of 1-[(1S)-1-(tertbutoxycarbonyl)propyl]-5-oxo-3-pyrrolidinecarboxaldehyde 396: 1H NMR (250 MHz, (CDCl3): 0.91 (t, 3H), 1.44 (s, 9H), 1.55-1.77 (m, 1H), 1.90-2.15 (m, 1H), 2.63-2.82 (m, 2H), 3.47-3.61 (m, 1H), 3.65-3.79 (m, 1H), 3.83-3.94 (m, 1H of one of the diastereoisomers), 4.48-4.62 (m, 1H), 9.74 (s (broad), 1H).

Provenance & Evidence