A New Germanium-Based Linker for Solid Phase Synthesis of Aromatics: Synthesis of a Pyrazole Library
作者:Alan C. Spivey、Christopher M. Diaper、Harry Adams、Andrew J. Rudge
DOI:10.1021/jo000401x
日期:2000.8.1
An efficient synthesis of chlorogermane linker 12 is described. Economic introduction of germanium into this linker is accomplished by insertion of dichlorogermylene [from germanium(IV) chloride] into the homobenzylic C-Cl bond of 4-(2-chloroethyl)phenol 1. Using linker 12, transmetalation with lithiated 4-acetophenone, 3-acetophenone, and 4-(4'methoxy)biphenyl followed by Mitsunobu-type coupling to
[reaction: see text] A straightforward synthesis of ibudilast-related pyrazolo[1,5-f]phenanthridines is accomplished by a tandem amine-exchange/heterocyclization of arylenaminones followed by an intramolecular biaryl coupling of the so-formed diarylpyrazoles. The direct, environmentally convenient ring-closure of the latter pyrazole intermediates, which show a close resemblance to the antiinflammatory
Copper-mediated tandem ring-opening/cyclization reactions of cyclopropanols with aryldiazonium salts: synthesis of <i>N</i>-arylpyrazoles
作者:Jidan Liu、Erjie Xu、Jinyuan Jiang、Zeng Huang、Liyao Zheng、Zhao-Qing Liu
DOI:10.1039/c9cc09657d
日期:——
A general method for the synthesis of structurally diverse N-arylpyrazoles from readily available cyclopropanols and aryldiazonium salts is disclosed. The reaction was conducted at room temperature within minutes with a broad substrate scope and excellent regioselectivity.
Toward Safer Processes for C−C Biaryl Bond Construction: Catalytic Direct C−H Arylation and Tin-Free Radical Coupling in the Synthesis of Pyrazolophenanthridines
pyrazolo[1,5-f]phenanthridine derivatives has been efficiently synthesized by a short, straightforward sequence. A tandem amine-exchange/heterocyclization of enaminones was successfully applied to the regioselective preparation of 1,5-diarylpyrazole intermediates with structure resemblance to relevant nonsteroidal anti-inflammatory drugs such as celecoxib or tepoxalin. The final key step, cyclization by intramolecular