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
Dramatic effects of the electrolyte cation on the selectivity of electroreductive cycloaddition reactions of bis(enones)
作者:Greg A.N. Felton、Nathan L. Bauld
DOI:10.1016/j.tetlet.2004.09.094
日期:2004.11
The nature of the electrolyte cation (Li, Na, K, Ag, Mg, Ba) exerts a dramatic effect upon the diastereoselectivity of the intramolecular cyclobutanation reactions of several bis(enones). The formation of cis as against trans cyclobutanes is strongly favored by magnesium ions, presumably via a chelation effect, and becomes exclusive in the case of barium. The latter ion has the additional surprising effect of enhancing the amount of Diels-Alder cycloaddition as opposed to cyclobutanation. (C) 2004 Elsevier Ltd. All rights reserved.
Chemically Induced Anion Radical Cycloadditions: Intramolecular Cyclobutanation of Bis(enones) via Homogeneous Electron Transfer
作者:Jingkui Yang、Greg A. N. Felton、Nathan L. Bauld、Michael J. Krische
DOI:10.1021/ja030543j
日期:2004.2.1
The first examples of anionradical cycloaddition induced by homogeneous electrontransfer from chemical agents are described. Specifically, upon exposure to chrysene anionradical, bis(enone) substrates are found to engage in stereoselective intramolecular [2 + 2] cycloaddition. These studies, along with the corresponding electrochemically initiated reactions, provide insight into this fundamentally
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