Titanocene‐Catalyzed [2+2] Cycloaddition of Bisenones and Comparison with Photoredox Catalysis and Established Methods
作者:Zhenhua Zhang、Julius B. Stückrath、Stefan Grimme、Andreas Gansäuer
DOI:10.1002/anie.202102739
日期:2021.6.21
Cp2Ti(TFA) is a broadly applicable catalyst for the [2+2] cycloaddition of bisenones by inner-sphere electron transfer. The attractiveness of this mechanism is shown by comparison with outer-sphere ET methods. DFT calculations show that the reaction proceeds through a unique unfavorable 5-exo (the rate-determining step) and a favorable 4-exo cyclization.
Electrochemically initiated, intramolecular anionradical cyclobutanations of bis(enones) and related substrates are presented. The formation of novel anionradical Diels–Alder adducts in minor amounts is also observed. Total yields of pericyclic products, which include both cis- and trans-cyclobutanes and a single Diels–Alder adduct, are generally high (51–88%), with electrocatalytic factors in the
Anion Radical [2 + 2] Cycloaddition as a Mechanistic Probe: Stoichiometry- and Concentration-Dependent Partitioning of Electron-Transfer and Alkylation Pathways in the Reaction of the Gilman Reagent Me<sub>2</sub>CuLi·LiI with Bis(enones)
作者:Jingkui Yang、David F. Cauble、Adam J. Berro、Nathan L. Bauld、Michael J. Krische
DOI:10.1021/jo048499t
日期:2004.11.1
species present at higher concentration induce Gilman alkylation en route to products 2a−2e, the species present at lower concentration provide products of catalytic [2 + 2] cycloaddition, 3a−3e. Moreover, upon electrochemical reduction of the bis(enones) 1a−1e, or chemically induced single-electron transfer from arene anion radicals, the very same [2 + 2] cycloadducts 3a−3e are formed. The collective data