Reduction of hydrazines to amines with low-valent titanium reagent
作者:Fang Ren、Yan Zhang、Lan Hu、Meiming Luo
DOI:10.3998/ark.5550190.0014.313
日期:——
The N,N bond cleavage in hydrazines to amines via low-valenttitaniumreagent prepared in situ by treatment of TiCl4 with Mg powder in THF or CH2Cl2-Et2O is described. The reaction proceeds smoothly under mild conditions to afford amines in good to excellent yields with diverse functional group tolerance such as chloride, methoxyl, benzyloxyl, ester, acyl, as well as C,C double bonds and benzyl-nitrogen
Photoswitching of the coordination number of silicon between four and five in allyldifluoro[2-(phenylazo)phenyl]silane, which was confirmed by X-ray analysis and multinuclear NMR spectroscopy, caused multistep reactions to proceed or stop, yielding tetrafluoro[2-(1-allyl-2-phenylhydrazino)phenyl]silicate without altering other reaction conditions.
First allylboration of organic compounds with the NN double bond. Synthesis of N-allylpyrazolidines and allyl-1,2-diphenylhydrazine
作者:Ivan P. Klimenko、Andrey F. Medvedev、Victor A. Korolev、G.D. Kolomnikova、Yury V. Tomilov、Yuri N. Bubnov
DOI:10.1016/j.jorganchem.2009.02.012
日期:2009.6
Triallylborane adds to the NN doublebond of pyrazolines 1 and 2 at 0 °C giving after deboronation the corresponding N-allylpyrazolidines 4 and 5. Further transformations of allylpyrazolidine 4 including the cyclopropane ring opening were studied. Allylboration of azobenzene with triallylborane gives rise to 1-allyl-1,2-diphenylhydrazine.
Cobalt-catalyzed borylative reduction of azobenzenes using pinacolborane is developed. The simple cobalt chloride catalyst and reaction conditions make this protocol attractive for hydrazobenzene synthesis. This borylative reduction shows good functional group compatibility and can be readily scaled up to the gram scale. Preliminary mechanistic studies clarified the proton source of the hydrazine products
Effective strategy for the systematic synthesis of hydrazine derivatives
作者:Aleksei Bredihhin、Uno Mäeorg
DOI:10.1016/j.tet.2008.04.096
日期:2008.7
A new and efficient strategy for the systematic synthesis of hydrazine derivatives is reported. It allows the synthesis of up to tetrasubstituted hydrazine derivatives with minimal number of steps using only one protecting group or without any of them at all. Simple and readily available starting materials such as hydrazine hydrate or phenylhydrazine can be used. A variety of substrates were used to investigate scope and limitations of this strategy, additionally one full synthetic sequence was performed. (C) 2008 Elsevier Ltd. All rights reserved.