A novel catalytic enantioselective tandem transetherification–intramolecular hetero Diels–Alder reaction of methyl (E)-4-methoxy-2-oxo-3-butenoate with δ,ε-unsaturated alcohols

✍ Scribed by Eiji Wada; Hidetaka Koga; Govindaraj Kumaran

• Publisher: Elsevier Science
• Year: 2002
• Tongue: French
• Weight: 98 KB
• Volume: 43
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(02)02320-1

✦ Synopsis

A novel asymmetric tandem transetherification-intramolecular hetero Diels-Alder reaction of methyl (E)-4-methoxy-2oxo-3-butenoate with d,o-unsaturated alcohols has been found to be catalyzed by optically active complexes based on bis(oxazoline) (box) chiral ligands and copper(II) cations. The catalyst derived from the (S,S)-tert-Bu-bis(oxazoline) and Cu(SbF 6 ) 2 in the presence of 5 A , molecular sieves was highly effective to afford corresponding trans-fused hydropyranopyran derivatives in good yield (up to 90%) with high enantiomeric excess (up to 98% ee).