A simple technique of using novel thread-holding and knot-pushing forceps for extracorporeal knot-tying
摘要:
We designed some novel knot-pushing forceps for extracorporeal knot-tying and describe herein our simple technique of utilizing them. These forceps are modified only by a single l-mm hole between their jaws, which hold a thread and push the knot toward the ligating tissue. The application of this simple device was handled well by surgeons beginning to perform advanced endoscopic surgery. The simple modification explained in this report seems applicable to most of the forceps currently used.
phenol as a directing group, high regioselectivity, good substrate scope, mild reaction conditions, and high efficiency. To the best of our knowledge, this is the first example of a regioselective C−H alkenylation of unprotected phenols utilizing phenolic hydroxyl group as a directing group. The alkenylation of unprotected tyrosine and intramolecular cyclization are also successfully carried out under
Visible-Light-Induced C(sp<sup>2</sup>)–C(sp<sup>3</sup>) Coupling Reaction for the Regioselective Synthesis of 3-Functionalized Coumarins
作者:Ke Zhang、Li Qiao、Jianwei Xie、Zhenwei Lin、Hanjie Li、Ping Lu、Yanguang Wang
DOI:10.1021/acs.joc.1c00848
日期:2021.7.16
A photocatalysis strategy for the regioselective synthesis of 3-functionalized coumarins is reported. With visible light irradiation, a direct and regioselective C(sp2)–C(sp3) coupling reaction of 3-(2-hydroxyphenyl)acrylates with ethers or thioethers occurs by using Ru(bpy)3Cl2·6H2O as a photocatalyst and TBHP as an oxidant. The cascade process involves alkenylation of the C(sp3)–H bond of ethers
Cascade Synthesis of 4-Arylcoumarins: Pd-Catalyzed Arylations and Cyclizations with (<i>E</i>
)-Ethyl 3-(2-Hydroxyaryl)acrylates and Triarylantimony Difluorides
The reactions of 3‐(2‐hydroxyaryl)acrylates with triarylantimony difluorides in the presence of Pd(OAc)2 and 2,2'‐bipyridyl under aerobic conditions afforded 4‐arylcoumarins in good‐to‐excellent yields with all of the arylgroups in the triarylantimony difluoride transferred to the coupling products. This protocol increases the synthetic scope of 4‐arylcoumarins, especially those bearing electron‐withdrawing
regioselective synthesis of 3-trifluoromethylated coumarins. The reaction was performed by using the Togni reagent as the CF3 source under mild conditions and showed good functional- group tolerance. The scope of this copper-mediated method was further expanded to the synthesis of 3-trifluoromethylated carbostyrils starting from ortho-aminocinnamic derivatives. Interestingly, a sequential one-pot synthesis of
Reaction of nitrosalicylaldehydes (1) with carbethoxymethylenetriphenylphosphorane in Et(2)NPh, in Ph(2)O, and in the absence of solvent (neat) at 210-215 degrees C was investigated. Reaction of 3-nitrosalicylaldehyde (1d) in Et(2)NPh afforded the benzoxazole (6) and the aminocoumarin (3e) along with the expected coumarin (3d). It was clarified that the origin of carbon-unit introduced for the formation of the benzoxazole ring came from the alkyl group of solvent.