Synthesis of Organochalcogen Propargyl Aryl Ethers and Their Application in the Electrophilic Cyclization Reaction: An Efficient Preparation of 3-Halo-4-Chalcogen-2<i>H</i>-Benzopyrans
作者:Benhur Godoi、Adriane Sperança、Davi F. Back、Ricardo Brandão、Cristina W. Nogueira、Gilson Zeni
DOI:10.1021/jo900307k
日期:2009.5.1
atom of the electrophilic chalcogen species. Additional versatility in this process was demonstrated with respect to a diverse array of functionality in the aromatic ring at propargyl aryl ethers. These propargyl aryl ethers, bearing the chalcogen group, underwent highly selective intramolecular cyclizations when treated with I2 or ICl affording 3-iodo-4-chalcogen-2H-benzopyrans. The results demonstrated
Selenium-promoted electrophilic cyclization of arylpropiolamides: synthesis of 3-organoselenyl spiro[4,5]trienones
作者:Ana Maria S. Recchi、Pedro H. P. Rosa、Davi F. Back、Gilson Zeni
DOI:10.1039/d0ob00609b
日期:——
3-organoselenyl-quinolinone derivativeformation via 6-endo-dig was avoided using an electrophilic organoselenium species in a metal-free protocol. The use of phenylselenyl bromide (1.3 equiv.), as the electrophilic source, in nitromethane (3 mL) at 90 °C enabled the cyclization of N-(2-methoxyphenyl)-N-methyl-3-phenylpropiolamides, giving 3-organoselenyl[4,5]triene-2,6-dione derivatives. The extension of the
Hydrozirconation of acetylenic chalcogenides. Synthesis and reactions of zirconated vinyl chalcogenide intermediates
作者:Miguel J. Dabdoub、Mauro L. Begnini、Palimécio G. Guerrero
DOI:10.1016/s0040-4020(98)00014-3
日期:1998.3
Acetylenic tellurides react with Cp2Zr(H)Cl in THF at room temperature to give the alpha-zirconated vinyl telluride intermediates 39, which react with a wide range of electrophiles to give several types of trisubstituted olefins, such as alpha-halo vinyl tellurides, ketene telluro(seleno) acetals, ketene telluro acetals, and vinylic tellurides of Z configuration. Acetylenic selenides undergo similar reactions, but a lack of regioselectivity results in the formation of a mixture of alpha-zirconated 19 and beta- zirconated 20 vinylic selenide intermediates. After a derailed study was established that the use of 2.0 equivalents of Cp2Zr(H)Cl is crucial to perform the total hydrozirconation of acetylenic selenides or tellurides. (C) 1998 Elsevier Science Ltd. All rights reserved.
Regio- and Stereoselective Conversion of Terminal Alkylselenoacetylenes into (E)-2-Alkylseleno-1-Vinylic Iodides via Hydroboration-Iodination
作者:De-Yu Yang、Xian Huang
DOI:10.1080/00397919608004786
日期:1996.12
The hydroboration of terminal alkylselenoacetylenes 1 in the presence of 3 mol% of Pd (PPh(3))(4) with catecholborane 2 followed by hydrolysis, undergo a rapid reaction with iodine under the influence of sodium hydroxide at-10 degrees C in THF to afford a novel method for the regio-and stereospecific synthesis of (E)-2-alkylseleno-1-vinyl iodides 4.
The Hydroboration-Iodination of Dialkylselenoacetylenes to Vinylic Diselenides
作者:De-Yu Yang、Xian Huang
DOI:10.1055/s-1997-959
日期:1997.8
The hydroboration of dialkylselenoacetylenes 1, generated from alkylseleno bromides and sodium acetylide in liquid ammonia, with dicycloalkylboranes followed by iodination under basic condition produced (Z)/(E)-vinylic diselenides (2/3). The reaction proceeds with a transfer of one cycloalkyl group and smoothly to give major 2 and minor 3 in almost quantitative ratio (2:3=93:7 to 97:3). The hydroboration-iodination process provides a general method for synthesis of (Z)-vinylic diselenides containing cyclic systems.