Cobalt‐Catalyzed Formal [4+2] Cycloaddition of α, α′‐Dichloro‐ortho‐Xylenes with Alkynes1. (27th August 2014)

• Record Type: Journal Article
• Authors: Komeyama, Kimihiro; Okamoto, Yuji; Takaki, Ken
• Is Part Of: Angewandte Chemie. Volume 126:Number 42(2014)
• Page Start: 11507
• Page End: 11510
• Publication Date: 2014-08-27
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201406807
• Languages: English
• ISSNs: 0044-8249

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A formal [4+2] cycloaddition of α, α′‐dichloro‐<italic>ortho</italic>‐xylenes with various alkynes has been developed using a low‐valent cobalt catalyst. The transformation has a wide substrate scope and high functional‐group tolerance and led to 1, 4‐dihydronaphthalenes. The formed cycloadducts were easily aromatized with MnO₂ under air. A mechanistic investigation suggests that the transformation proceeds through a benzyl cobaltation of alkyne, not the classical Diels–Alder reaction of <italic>ortho</italic>‐quinodimethanes. This methodology provides a straightforward and streamlined access to linearly expanded π‐conjugated aromatics.</p> </abstract>