Reduction of hydrazines to amines with aqueous solution of titanium(iii) trichloride
N-N bond cleavage in hydrazines is widely used in the preparation of amines and thus occupies a significant place in organic synthesis. In this paper, we report a new method for the reductive cleavage of N-N bonds in hydrazines by commercially available and cheap aqueous titanium(iii) trichloride. The reaction proceeds smoothly under a broad pH range from acidic to neutral and basic conditions to afford amines in good yields. This method is compatible with substrates containing functionalities such as C-C double bonds, benzyl-nitrogen bonds, benzyloxy and acyl groups. The Royal Society of Chemistry 2011.
Zhang, Yan,Tang, Qiang,Luo, Meiming
supporting information; experimental part
p. 4977 - 4982
(2011/08/05)
First allylboration of organic compounds with the N{double bond, long}N double bond. Synthesis of N-allylpyrazolidines and allyl-1,2-diphenylhydrazine
Triallylborane adds to the N{double bond, long}N double bond 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 we
Klimenko, Ivan P.,Medvedev, Andrey F.,Korolev, Victor A.,Kolomnikova,Tomilov, Yury V.,Bubnov, Yuri N.
experimental part
p. 2106 - 2109
(2009/10/30)
Effective strategy for the systematic synthesis of hydrazine derivatives
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.
Bredihhin, Aleksei,M?eorg, Uno
p. 6788 - 6793
(2008/12/20)
Intramolecular allylation of the azo group of 2-(allylsilyl)azobenzenes and its photocontrol
Pentacoordinate allylsilanes bearing an azobenzene moiety were synthesized and their structures were elucidated. The reaction of allyldifluorosilane (E)-7a with BF3 · OEt2 did not proceed, but (E)-7a was allowed to react with a fluoride ion to give tetrafluorosilicate 8a via intramolecular allyl-migration from the silicon atom onto the azo group. Activation of both the nucleophilic and electrophilic parts by the Si?N interaction was found to be important for promotion of the allyl-migration reaction. The azobenzene moiety of the allylsilane was reversibly isomerized by photoirradiation. The (Z)-7a formed by photoirradiation of (E)-7a is in a tetracoordinate state in contrast to the (E)-7a, and it did not react with a fluoride ion at all under the conditions where (E)-7a reacted quantitatively. The reactivity was successfully controlled without changing any conditions other than the change of the coordination number of the silicon atom induced by photoirradiation.
Reactivity control of an allylsilane bearing a 2-(phenylazo)phenyl group by photoswitching of the coordination number of silicon
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 tetraf