Details

Autor(en) / Beteiligte

• Zill, Nicolas
• Schoenfelder, Angèle
• Girard, Nicolas
• Taddei, Maurizio
• Mann, André

Titel

Stereoselective Multicomponent Assembly of Enantiopure Oxazolopiperidines and -azepines

Ist Teil von

• Journal of organic chemistry, 2012-03, Vol.77 (5), p.2246-2253

Ort / Verlag

Washington, DC: American Chemical Society

Erscheinungsjahr

2012

Quelle

MEDLINE

Beschreibungen/Notizen

• A multicomponent reaction (MCR) based on a cyclohydrocarbonylation (CHC) driven by hydroformylation was set up toward the efficient diastereoselective preparation of oxazolopiperidines (4a–e) and -azepines (7a–d). The bicyclic oxazolidines were obtained from chiral N-alkenylamino alcohols via transient cyclic iminium intermediates that underwent an intramolecular cyclization from the appendant oxygen. On the basis of a series of different experimental conditions, the diastereocontrol observed during the formation of the oxazolidines is best explained by the stereoelectronic effect induced by an A1,3-strain in a common cyclic iminium intermediate (A). This new sequence is suitable for diversity oriented syntheses, allowing the preparation of enantiopure (S)- and (R)-coniceine in five steps from commercially available material.