A new strategy in enantioselective intramolecular hetero Diels–Alder reaction: catalytic double asymmetric induction during the tandem transetherification–intramolecular hetero Diels–Alder reaction of methyl (E)-4-methoxy-2-oxo-3-butenoate with rac-6-methyl-5-hepten-2-ol

✍ Scribed by Hidetaka Koga; Eiji Wada

• Publisher: Elsevier Science
• Year: 2003
• Tongue: French
• Weight: 340 KB
• Volume: 44
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(02)02706-5

✦ Synopsis

An efficient catalytic double asymmetric induction during the tandem transetherification-intramolecular hetero Diels-Alder reaction has been developed. The enantioselective tandem reaction of methyl (E)-4-methoxy-2-oxo-3-butenoate with rac-6-methyl-5-hepten-2-ol has been achieved to provide methyl (2R,4aS,8aR)-3,4,4a,8a-tetrahydro-2,5,5-trimethyl-2H,5Hpyrano[4,3-b]-pyran-7-carboxylate in good yield with effective kinetic resolution (up to 95% selectivity), high diastereoselectivity (up to 92% de), and high enantioselectivity (up to 97% ee) in the presence of (S,S)-tert-Bu-bis(oxazoline)-Cu(SbF 6 ) 2 and 5 A , molecular sieves.