Electron Transfer Initiated Heterogenerative Cascade Cyclizations: Polyether Synthesis under Nonacidic Conditions
作者:V. Satish Kumar、Danielle L. Aubele、Paul E. Floreancig
DOI:10.1021/ol0261074
日期:2002.7.1
been employed to initiate heterogenerative cascade cyclization reactions that form polyether compounds under essentially neutral conditions. The reactions proceed through mesolytic benzylic carbon-carbonbond cleavages of homobenzylic ether-derived radical cations followed by intramolecular epoxonium ionformation, leading to further cyclizations. Both oligotetrahydrofuran and tetrahydropyran structures
Asymmetric Catalysis via Cyclic, Aliphatic Oxocarbenium Ions
作者:Sunggi Lee、Philip S. J. Kaib、Benjamin List
DOI:10.1021/jacs.6b11993
日期:2017.2.15
A direct enantioselectivesynthesis of substituted oxygen heterocycles from lactol acetates and enolsilanes has been realized using a highly reactive and confined imidodiphosphorimidate (IDPi) catalyst. Various chiral oxygen heterocycles, including tetrahydrofurans, tetrahydropyrans, oxepanes, chromans, and dihydrobenzofurans, were obtained in excellent enantioselectivities by reacting the corresponding
Oxidatively generated electrophiles as initiators of epoxide cascade cyclization processes
作者:V. Satish Kumar、Shuangyi Wan、Danielle L. Aubele、Paul E. Floreancig
DOI:10.1016/j.tetasy.2005.08.055
日期:2005.10
Oxidatively generated oxocarbenium ions are shown to be effective promoters of polyepoxide cascade cyclization reactions to form polyether compounds. The reaction conditions are neutral, ensuring that background acid-mediated processes are not operative and that other acid-sensitive functional groups, such as acetals, can be incorporated into cyclization substrates. While 5-exo pathways are more common that 6-endo pathways, a rational design has been employed to access tetrahydropyranyl ethers. (c) 2005 Elsevier Ltd. All rights reserved.