Anodic cyclization reactions: probing the chemistry of N,O-ketene acetal derived radical cations
作者:Yung-tzung Huang、Kevin D. Moeller
DOI:10.1016/j.tet.2006.04.009
日期:2006.7
The chemical reactivity of radical cations derived from N,O-ketene acetals has been examined and compared with the reactivity of radical cations derived from both ketene dithioacetals and enol ethers. Synthetically, the N,O-ketene acetal radical cations lead to more efficient cyclization reactions than either the ketene dithioacetal or enol ether derived radical cations. Cyclic voltammetry experiments
Preparation of Oxepanes, Oxepenes, and Oxocanes by Iodoetherification using Bis(<i>sym</i>-collidine)iodine(I) Hexafluorophosphate as Electrophile
作者:Yves Brunel、Gérard Rousseau
DOI:10.1021/jo960506t
日期:1996.1.1
Oxepanes have been obtained in good yields (40-95%) by iodoetherification of unsaturated alcohols using bis(sym-collidine)iodine(I) hexafluorophosphate (1) as electrophile, either by 7-exo-mode or 7-endo-mode cyclizations. 4-Oxepenes could also be formed from 4,6-heptadien-1-ols; the presence of a substituent on the carbon 6 appeared necessary, while for steric reasons the presence of a substituent on the carbon 7 was unfavorable. Oxocanes could be obtained in moderate yields (18-27%).
One-flask, regiospecific conversions of allylic alcohols into 2-carbon-extended, conjugated dienoate esters. Use of a new sulfinyl orthoester
作者:Gary H. Posner、R. David Crouch、Chris M. Kinter、Jean Christophe Carry
DOI:10.1021/jo00025a008
日期:1991.12
Sixteen differently substituted primary and secondary allylic alcohols are shown to react with sulfinyl orthoacetate 1 at 100-degrees-C sequentially via a [3,3] sigmatropic rearrangement and then a beta-elimination of benzenesulfenic acid to form conjugated dienoate esters 5-13 in 45-95% yields. This one-flask, intramolecular carbon-carbon bond-forming process represents a simple and convenient method for regiospecific gamma-attachment of a two-carbon (ethoxycarbonyl)methylene unit via the synthetic equivalent of an S(N)2' process. Two examples are given in which rationally designed dienoates 20 and 24, prepared via this one-flask process and carrying a pendant alkene unit, undergo intramolecular 2 + 4 cycloaddition producing bicyclic cyclohexenes 21 and 25.
Construction of dihydropyran-bridged macrocycles by inverse-electron-demand Diels–Alder reaction
作者:Xiaomei Dong、Qingxia Wang、Qian Zhang、Shuai Xu、Zhihong Wang
DOI:10.1016/j.tet.2013.10.101
日期:2013.12
A variety of dihydropyran-bridged macrocyclic structures were constructed by the inverse-electron-demand Diels Alder reaction of 2-oxo-4-aryl-but-3-enoates. Controlling of the tether length and the position of the activating substituent in the substrates would guide the reaction to the formation of four different types of polycyclic frames, namely bicyclic [n.3.1], bicyclic [n.2.2], tricyclic [n.3.1.1], and tricyclic [n.2.2.2] macrocycles. The intermolecular/intramolecular selectivity of the Diels Alder reaction was virtually governed by the tether length. The reactions were carried out rapidly under mild conditions, and offered a practical method for creating bridged polycyclic structures with large rings from acyclic precursors. (C) 2013 Elsevier Ltd. All rights reserved.
Intramolecular Anodic Olefin Coupling Reactions: A New Approach to the Synthesis of Angularly Fused, Tricyclic Enones
作者:Luzviminda V. Tinao-Wooldridge、Kevin D. Moeller、Christine M. Hudson
DOI:10.1021/jo00088a019
日期:1994.5
A number of intramolecular anodic olefin coupling reactions have been examined in order to determine the feasibility of using a sequential electrochemical oxidation-aldol condensation approach for constructing polycyclic enones. Initially, substrates comprised of an aldehyde enol ether tethered to a ketone enol ether were examined. In a model study, it was shown that such a substrate could lead to a successful electrochemical oxidation-aldol condensation sequence. However, the difficulties associated with both the synthesis and the poor stability of the ketone enol ethers greatly reduced the potential utility of this approach. This problem was circumvented by taking advantage of the compatibility of allylsilane groups with the electrolysis reaction. In these examples, ozonolysis of the electrochemical cyclization product afforded the 1,4-dicarbonyl substrate needed for the aldol condensation. The use of the less reactive allylsilane group in the electrochemical reaction still allowed for the construction of quaternary carbons. Finally a pair of angularly fused, tricyclic enones were synthesized. The regiochemistry of the enone in the product could be controlled by the proper choice of the substrate for the electrolysis and manipulation of the resulting cyclized product.