addition/cyclization/halogen atomtransferbetween alkynes and α-halogeno-γ, δ-unsaturated carbonyl compounds for the synthesis of various substituted cyclopentenes is described. Since up to four Csp3–Csp2 bonds, two Csp3–Br bonds, and two carbocycles can be established in a single reaction, this 100% atom-efficient reaction exhibits the advantages of wide substrate scope, high functional group tolerance, and step-economics
Intermolecular Visible-Light Photoredox Atom-Transfer Radical [3+2]-Cyclization of 2-(Iodomethyl)cyclopropane-1,1-dicarboxylate with Alkenes and Alkynes
作者:Xiangyong Gu、Xiang Li、Yue Qu、Qi Yang、Pixu Li、Yingming Yao
DOI:10.1002/chem.201301943
日期:2013.9.2
visible‐light‐promoted, tin/boron‐free intermolecular [3+2] atom‐transfer radical cyclization reaction was developed by using iridium polyphenylpridinyl complex as the sensitizer (see scheme). 2‐(Iodomethyl)cyclopropane‐1,1‐dicarboxylate reacted with various alkenes and alkynes to form cyclopentane and cyclopentene derivatives.
Intermolecular Photocatalytic C–H Functionalization of Electron-Rich Heterocycles with Tertiary Alkyl Halides
作者:Corey Stephenson、Elizabeth Swift、Theresa Williams
DOI:10.1055/s-0035-1561320
日期:——
The coupling of tertiary alkyl halides with electron-rich arenes is promoted by visible-light photoredox catalysis. Tris[2-phenylpyridinato-C 2,N]iridium(III) [Ir(ppy)3] was the optimal catalyst, enabling direct reduction of the halide from the excited state, and thereby eliminating the requirement for a stoichiometric electron donor. High yields were obtained when the aromatic component was used in
A photosensitizer-free, highly efficient sunlight-promoted tandem [3+2]/[4+2] annulation of unsaturated α-bromocarbonyls with o-alkynylanilines was developed, and allowed for convenient synthesis of fused benzobicyclic skeletons. The reaction was clean and practical in mild conditions and showed excellent functional group compatibility.
A novel visible-light photocatalytic bicyclization of β-alkynyl propenones with α-bromocarbonyls for highly diastereoselective synthesis of richly decorated syn-fluoren-9-ones is described. The reaction proceeds via a radical-triggered 5-exo-dig cyclization/1,6-H-abstraction/6-endo-trig cyclization cascade and offers a new and practical method for the assembly of 6/5/6 carbocyclic skeletons via C(sp3)–H