(2S)-1-(2-methylpropanoyl)pyrrolidine-2-carboxylic acid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: [Isobutyryl9 ]Didemnin B (33) and [Isobutyryl9, D-Pro8 ] Didemnin B (34). L-Pro (1.15 g, 0.01 mol) was treated with isobutyric anhydride in a procedure like the N-propionylproline synthesis to give N-isobutyrylproline (1.8 g, 96%): fine crystals, mp 80-82° C.; [α]D25 -8.7° (c 1.56, CHCl3). 1H NMR Anal. (C9H15NO3) C, H, N.