Browsing by Author "Scherberich, Paul"

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    A novel synthetic route to L-proline (Amino acids ; 7)
    (1986) Drauz, Karl-Heinz; Kleemann, Axel; Martens, Jürgen; Scherberich, Paul; Effenberger, Franz
    Reaction of L-5-oxoproline esters L-2 with phosgene at 0° C gives L-5,51-dichloro-1-(chlorocarbonyl)proliene esters L-6 ,which readily lose hydrogen chloride to form L-5-chloro-1-(chloroarbonyl)-4,5-dehydroproline esters L-7. Catalytic hydrogenation (Pd/C, 180 bar) of L-7 yields L-1-(chlorocarbonyl)proline esters L-15 and thence, upon hydrolysis, L-proline ( L17 ). A "one-pot reaction" for the whole sequence is described, starting from easily accessible L-5-oxoproline esters and yielding L-proline in 78% overall yield and 99.7% optical purity.