meta-Directing Cobalt-Catalyzed Diels–Alder Reactions

✍ Scribed by Gerhard Hilt; Judith Janikowski; Wilfried Hess

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 108 KB
• Volume: 45
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.200601974

✦ Synopsis

The Diels-Alder reaction has belonged to the arsenal of synthetic organic chemists for decades as can be seen in the large number of applications in natural-product synthesis and of biologically active compounds. [1] The usefulness of the Diels-Alder reaction is based on the cyclic transition state which allows the transfer of the stereochemical information in the starting material E-or Z-selectively into cis-or transconfigured products. Furthermore, the regiochemistry of the intermolecular Diels-Alder reaction can be predicted by the Woodward-Hoffmann rules and the therein implied ortho/ para rules. [2] While the ortho/para-selectivity of the thermal Diels-Alder reaction allows access to ortho-or para-substituted products (such as 1, Scheme 1) the intermolecular reaction is limited to the generation of para-substituted products when starting from isoprene, the meta-substituted products of type 2 (Scheme 1) can not be accessed. Only the