Sodium Hydroxide → (2S,4R)-1-allyloxycarbonyl-2-methoxycarbonyl-4-hydroxypyrrolidine

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Reaction Steps

To a solution of 4-hydroxyproline methyl ester hydrochloride (Rosen et al, Synthesis, 40, 1988) (60.4 mMol) in water (10 ml) and THF (20 ml), at 0° C., was added dropwise allyl chloroformate (70 mMol) in THF (20 ml). The solution was maintained at a slightly basic pH by the simultaneous addition of 4N sodium hydroxide (144 mMol). The mixture was stirred at 0° for 1 hour. The aqueous layer was separated and washed, twice, with dichloromethane (25 ml). The organic layers were combined, dried and evaporated to give N-allyloxycarbonyl hydroxyproline methyl ester as a pale yellow oil (86%): NMR (CDCl3) 2.2(m, 3H); 3.58(m, 2H); 3.73(2d, 3H); 4.54(m, 4H); 5.25(m, 2H); 5.9(m, 1H): M/S CI (M+H)+ =230.

Provenance & Evidence