Epoxides as Alkylating Reagents for the Catellani Reaction

• Published in: Angewandte Chemie International Edition Vol. 57; no. 13; pp. 3444 - 3448
• Main Authors: Cheng, Hong‐Gang, Wu, Chenggui, Chen, Han, Chen, Ruiming, Qian, Guangyin, Geng, Zhi, Wei, Qiang, Xia, Yuanyuan, Zhang, Jingyang, Zhang, Yuming, Zhou, Qianghui
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 19.03.2018; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Alkenes; Alkylation; Aromatic compounds; Carboxylic acids; Catalysis; Chemistry; Chemistry, Multidisciplinary; cooperative catalysis; C−H activation; Epoxides; Iodides; isochromans; oxa-Michael addition; Physical Sciences; Potassium; Reagents; Science & Technology; PALLADIUM/NORBORNENE CATALYSIS; ENANTIOSELECTIVE SYNTHESIS; REGIOSPECIFIC SYNTHESIS; cooperative catalysis; EFFICIENT SYNTHESIS; isochromans; oxa-Michael addition; C-H FUNCTIONALIZATION; C-H activation; NATURAL-PRODUCT SYNTHESIS; PALLADIUM-CATALYZED SYNTHESIS; ARYL IODIDES; epoxides; OXA-MICHAEL REACTION; C−H activation
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.201800573

We report a cooperative catalytic system comprising a PdII complex, XPhos, and the potassium salt of 5‐norbornene‐2‐carboxylic acid that enables the use of epoxides as alkylating reagents in the Catellani reaction, thereby expanding the existing paradigm of this powerful transformation. The potassium salt of inexpensive 5‐norbornene‐2‐carboxylic acid acts as both mediator and base in the process. This mild, chemoselective, scalable, and atom‐economical protocol is compatible with a wide variety of readily available functionalized aryl iodides and epoxides, as well as terminating olefins. The resulting products undergo facile oxa‐Michael addition to furnish ubiquitous isochroman scaffolds. A little cooperation can go a long way: A cooperative catalytic system comprising a PdII/XPhos complex and the potassium salt of 5‐norbornene‐2‐carboxylic acid, which serves dual roles as a mediator and a base, enabled the use of epoxides as alkylating reagents in the Catellani reaction (see scheme). The products could also undergo oxa‐Michael addition to furnish valuable isochroman scaffolds.