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Asymmetric Rhodium‐Catalyzed Hydrogenation Meets Gold‐Catalyzed Cyclization: Enantioselective Synthesis of 8‐Hydroxytetrahydroisoquinolines
Author(s) -
Hashmi A. Stephen K.,
Haufe Patrick,
Schmid Christoph,
Rivas Nass Andreas,
Frey Wolfgang
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600192
Subject(s) - stereocenter , rhodium , racemization , enantioselective synthesis , catalysis , chemistry , enantiomer , asymmetric hydrogenation , absolute configuration , stereochemistry , medicinal chemistry , organic chemistry
Different furyl‐substituted ( Z )‐dehydroamino acid derivatives were hydrogenated with the rhodium/Mandyphos(OMe)‐system to give enantiomeric excesses between 80 and 98 %. The absolute configuration of the newly formed stereogenic center was determined by anomalous diffraction to be R . These chiral furyl alanines were transferred into 8‐hydroxytetrahydroisoquinolines by employing gold‐catalyzed arene synthesis as the key step. During the latter reaction sequence, also including either a propargylation or a reduction, a protection of the hydroxy group, and a subsequent propargylation, no racemization of the stereogenic center was observed. With very electron‐rich furans, instead of the 8‐hydroxytetrahydroquinolines as products, furans anellated to seven‐membered rings with exocyclic CC double bonds are formed under the same reaction conditions.