Control of the Regio- and Stereoselectivity in Diels-Alder Reactions with Quinone Boronic Acids
作者:María C. Redondo、Marcos Veguillas、María Ribagorda、M. Carmen Carreño
DOI:10.1002/anie.200803428
日期:2009.1.2
The dienophilic reactivity of 2‐methyl‐substituted quinones has been substantially increased by the introduction of a boronicacid substituent, which makes them equivalent to a highly reactive quinone. The Diels–Alderreactions of these quinones are followed by spontaneous and stereoselective protodeboronation to give the trans‐fused adducts. The boron group is a temporal regiocontroller and leads to
Cycloadditions in mixed aqueous solvents: the role of the water concentration
作者:Theo Rispens、Jan B. F. N. Engberts
DOI:10.1002/poc.926
日期:2005.8
benzonitrile oxide with N-n-butylmaleimide. Plots of logk vs the molar concentration or volume fraction of water are approximately linear, but with a characteristic break around 40 M water. This break, absent for the RDA reaction, is ascribed to hydrophobic effects. Comparison with aqueous mixtures of the more hydrophobic 1-propanol shows that these mixtures induce qualitatively similar effects on the
Synthesis of Benzo- and Naphthoquinonyl Boronic Acids: Exploring the Diels-Alder Reactivity
作者:Marcos Veguillas、Maria C. Redondo、Isabel García、María Ribagorda、M. Carmen Carreño
DOI:10.1002/chem.200902796
日期:2010.3.22
dehydroboronation, depending on the substitution on both the quinone and diene partners. The boronic acid acts as a temporary controller, opening a direct access to trans‐fused meta‐regiosomeric adducts when 3‐methyl‐substituted 2‐quinonyl boronic acids react with dienes with a substituent at C‐1. A particularly valuable synthetic result was obtained in the reaction between 3,6‐dimethyl‐2‐quinonyl
作者:Ya-Fei Ji、Zhi-Min Zong、Xian-Yong Wei、Guang-Zhong Tu、Li Xu、Lin-Tao He
DOI:10.1081/scc-120016320
日期:2003.1.4
Abstract With (E/Z)-isomeric phytyl halides as side-chain materials, vitamin K 1 is synthesized via a Diels–Alder reaction to activate the free bridgehead hydrogen of 3 for the alkylation and a retro-Diels–Alder reaction to eliminate cyclopentadiene from 2 in a high yield, in which the configuration of the double bond in the phytyl side-chain is retained.