Aliphatic Radical Relay Heck Reaction at Unactivated C(sp3)−H Sites of Alcohols. Issue 6 (17th January 2019)

• Record Type: Journal Article
• Authors: Chuentragool, Padon; Yadagiri, Dongari; Morita, Taiki; Sarkar, Sumon; Parasram, Marvin; Wang, Yang; Gevorgyan, Vladimir
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 6(2019)
• Page Start: 1794
• Page End: 1798
• Publication Date: 2019-01-17
• Subjects: C−H activation -- Heck reaction -- palladium -- photochemistry -- radicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201812398
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The Mizoroki–Heck reaction is one of the most efficient methods for alkenylation of aryl, vinyl, and alkyl halides. Given its innate nature, this protocol requires the employment of compounds possessing a halogen atom at the site of functionalization. However, the accessibility of organic molecules possessing a halogen atom at a particular site in aliphatic systems is extremely limited. Thus, a protocol that allows a Heck reaction to occur at a specific nonfunctionalized C(sp 3 )−H site is desirable. Reported here is a radical relay Heck reaction which allows selective remote alkenylation of aliphatic alcohols at unactivated β‐, γ‐, and δ‐C(sp 3 )−H sites. The use of an easily installed/removed Si‐based auxiliary enables selective I‐atom/radical translocation events at remote C−H sites followed by the Heck reaction. Notably, the reaction proceeds smoothly under mild visible‐light‐mediated conditions at room temperature, producing highly modifiable and valuable alkenol products from readily available alcohols feedstocks. Abstract : A selective Heck reaction at β‐, γ‐, and δ‐C(sp 3 )−H sites of aliphatic alcohols has been developed. The radical hydrogen‐atom transfer/I‐atom translocation process, combined with the palladium‐catalyzed Heck reaction, allows selective remote alkenylation at unactivated C(sp 3 )−H sites under mild visible‐light‐induced conditions at room temperature. Neither exogenous oxidants nor photosensitizers are necessary.