Methanol → (2S,4S)-1-Benzyl 2-methyl 4-hydroxypyrrolidine-1,2-dicarboxylate

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Reaction Steps

6.5 g (0.024 mole) of N-carbobenzyloxy-cis-4-hydroxy-L-proline (J.A.C.S., 79, 189 (1957)] is dissolved in 65 ml. of methanol, stirred, and treated with 0.65 ml. of concentrated sulfuric acid. After stirring at room temperature for one-half hour, the solution is allowed to stand overnight. The bulk of solvent is removed on a rotary evaporator and the oily residue (13 g.) is taken up in 70 ml. of ether and washed with 35 ml. of 10% sodium bicarbonate solution. The wash is back extracted with 35 ml. of ether. The combined organic layers are dried (MgSO4), and the ether is evaporated to give 6.5 g. (96%) of product as a pale yellow viscous oil. [α]D25 -24° (c, 1% in chloroform).

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