Intramolecular photochemical reactions of 4-(.omega.-alkenyloxy)-6-methyl-2-pyrones having an alkoxycarbonyl group at the olefinic carbon chain
摘要:
Photochemical reactions of 4-(omega-alkenyloxy)-6-methyl-2-pyrones 4-8 were investigated. Photosensitized reactions of 2-pyrones 4-6 gave intramolecular [2 + 2] cycloadducts 14-16 as oxatricyclic lactones, site-, regio- and stereospecifically, but 7 and 8 gave no products. On the other hand, direct irradiations of 4 and 5 afforded cyclobutenecarboxylic acids 19 and 20, respectively. The intramolecular cycloaddition mechanism was also explained from the excited state of 2-pyrone calculated by means of the MNDO-CI method.
Cu-catalyzed carboboration of acetylene with Michael acceptors
作者:Tairan Cheng、Boxiang Liu、Rui Wu、Shifa Zhu
DOI:10.1039/d2sc02306g
日期:——
A copper-catalyzed three-component carboboration of acetylene with B2Pin2 and Michael acceptors is reported. In this reaction, a cheap and abundant C2 chemical feedstock, acetylene, was used as a starting material to afford cis-alkenyl boronates bearing a homoallylic carbonyl group. The reaction was robust and could be reliably performed on the molar scale. Furthermore, the resulting cis-alkenyl boronates
报道了铜催化乙炔与 B 2 Pin 2和 Michael 受体的三组分碳硼化反应。在该反应中,使用廉价且丰富的C2化学原料乙炔作为起始原料,得到带有同烯丙基羰基的顺式烯基硼酸酯。该反应很稳健,并且可以在摩尔规模上可靠地进行。此外,所得顺式烯基硼酸酯可以轻松转化为多种功能化分子。
Extraordinary aspects of bromo-functionalized multi-walled carbon nanotubes as initiator for polymerization of ionic liquid monomers
作者:Yu-Hsun Chang、Pei-Yi Lin、Ming-Sung Wu、King-Fu Lin
DOI:10.1016/j.polymer.2012.03.020
日期:2012.4
Two ionic liquid monomers, 1-(2-acryloyloxy-ethyl)-3-methyl-imidazol-1-ium iodide (AMImI) and 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide (AMBImI), were synthesized and polymerized through atom transfer radical polymerization (ATRP). Poly(AMImI)-grafted multi-walled carbon nanotubes (denoted as MWCNT-poly(AMImI)) could also be fabricated through "grafting from" method of ATRP using bromo-functionalized MWCNT (denoted as MWCNT-Br) as initiator but MWCNT-poly(AMBImI) could not. Based on the thermogravimetric analysis and high resolution transmission electron microscopy, AMBImI monomer has encapsulated the MWCNT-Br probably through the pi-pi: and cation-pi interactions invalidating the initiation capability of MWCNT-Br. Besides, by mixing AMBImI with MWCNT-Br directly at room temperature, the MWCNT-Br was coated with a thin layer of AMBImI, whereas MWCNT-Br could not physisorb AMImI. Both MWCNT-poly(AMImI) and AMBImI-encapsulated MWCNT were dispersed well in 1-methyl-3-propylimidazolium iodide ionic liquid. (C) 2012 Elsevier Ltd. All rights reserved.