A concise enantioselective entry to the synthesis of deoxy-azasugars.

R Martín, A Moyano, M A Pericàs, A Riera

Departament de Química Orgànica, Universitat de Barcelona, Spain. are@ursa.qo.ub.es

Organic letters 2000 Jan

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reaction: see text] A concise enantioselective preparation of oxazolidinylpiperidine 4, a key intermediate in the synthesis of glycosidase inhibitors such as 1-deoxymannojirimycin or 1-deoxygalactostatin, has been developed. Sharpless catalytic asymmetric epoxidation of (E)-2,4-pentadienol followed by treatment with allyl isocyanate afforded epoxy carbamate 8. Regioselective intramolecular ring opening promoted by sodium bis(trimethylsilyl)amide and ring-closing metathesis provided the bicyclic intermediate 4 in high enantiomeric purity. The four-step sequence takes place in 51% overall yield.