Palladium-Catalyzed Cleavage of α-Allenylic Aryl Ether toward Pyrazolemethylene-Substituted Phosphinyl Allenes and Their Transformations via Alkenyl C–P(O) Cleavage
摘要:
A palladium-catalyzed two-component coupling of allenylphosphine oxides with conjugated N-tosylhydrazones is revealed. For the first time, the cleavage of a-allenylic aryl ether toward pyrazolemethylene-substituted phosphinyl allenes enabled facile synthesis of combined motifs with pyrazole and allene. Moreover, the obtained adducts could be easily transformed to potential bioactive multifunctionalized phosphinates via a novel alkenyl C-P(O) cleavage.
Saturated aldehydes and ketones are converted via their p-toluenesulfonyl hydrazones to the corresponding alkanes using dichloro bis(1,4-diazabicydo[2.2.2]octane)(tetrahydroborato) zirconium(IV) (ZrBDC). The reactions were performed in DMF-sulfolane at 110 °C and gave the corresponding alkanes in high yields. Regioselectivity in the reduction of α,β-unsaturated carbonyl groups was also observed.
A base‐promoted three‐component coupling of carbon dioxide, amines, and N‐tosylhydrazones has been developed. The reaction is suggested to proceed via a carbocation intermediate and constitutes an efficient and versatile approach for the synthesis of a wide range of organic carbamates. The advantages of this method include the use of readily available substrates, excellent functional group tolerance
Metal-free and highly regioselective synthesis of N-heteroaryl substituted pyrazoles from α,β-unsaturated N-tosylhydrazones and heteroaryl chlorides
作者:Lin Zeng、Xiao-Qiang Guo、Zai-Jun Yang、Ya Gan、Lian-Mei Chen、Tai-Ran Kang
DOI:10.1016/j.tetlet.2019.07.034
日期:2019.8
β-unsaturated N-tosylhydrazones with N-heteroaryl chlorides was developed for the synthesis of N-heteroaryl pyrazole derivatives. This one-pot reaction provided bi(heteroaryl) derivatives in good to excellent yields and with excellent regioselectivity. The procedure is operationally simple and applicable to large-scale synthesis.
Copper(I)-Catalyzed Alkylation of Polyfluoroarenes through Direct CH Bond Functionalization
作者:Shuai Xu、Guojiao Wu、Fei Ye、Xi Wang、Huan Li、Xia Zhao、Yan Zhang、Jianbo Wang
DOI:10.1002/anie.201412450
日期:2015.4.7
The copper(I)‐catalyzed alkylation of electron‐deficient polyfluoroarenes with N‐tosylhydrazones and diazo compounds has been developed. This reaction uses readily available starting materials and is operationally simple, thus representing a practical method for the construction of C(sp2)C(sp3) bonds with polyfluoroarenesthroughdirectCHbondfunctionalization. Mechanistically, copper(I) carbene
A base-promoted cascade reaction of α,β-unsaturated <i>N</i>-tosylhydrazones with <i>o</i>-hydroxybenzyl alcohols: highly regioselective synthesis of <i>N-sec</i>-alkylpyrazoles
作者:Lian-Mei Chen、Juan Zhao、An-Jie Xia、Xiao-Qiang Guo、Ya Gan、Chuang Zhou、Zai-Jun Yang、Jun Yang、Tai-Ran Kang
DOI:10.1039/c9ob01780a
日期:——
N-sec-alkylpyrazoles through a base-promoted cascade cyclization/Michael addition reaction of α,β-unsaturated N-tosylhydrazones with ortho-hydroxybenzyl alcohols has been developed. The desired products containing di- or triaryl groups at the same carbon atom were afforded in good to excellent yields with excellent regioselectivities (>20 : 1). Moreover, a three-component reaction of ortho-hydroxybenzyl alcohols, α