Résumé

The diastereoselective Mannich reaction of functionalized aldehydes, using a phenethylamine-derived iminium precursor, by activation with prolines and prolinol derivatives have been studied. Optimized reaction conditions have been developed, allowing for scale-up and preparation of γ-amino alcohol derivatives on multi-gram scale from β-hydroxypropanal and -butanal, with diastereoselectivites of typically >73:27 and yields of >60 %. After chromatographic diastereoisomer separation, hydrogenolytic debenzylation, enantiomerically pure Fmoc-β2-Ser(tBu)-OH and Fmoc-β2-Thr(tBu)-OH were thus prepared on multi-gram scale in 6 steps and with overall yields of 24 % and 10 %, respectively, starting from commercially available starting compounds.

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