18841-76-4Relevant academic research and scientific papers
A novel one-pot two-component synthesis of tricyclic pyrano[2,3-b] quinoxalines
Goswami, Shyamaprosad,Adak, Avijit Kumar
, p. 221 - 224 (2005)
Tricyclic pyrano[2,3-b]quinoxalines 6 have been synthesized in one step by the reaction of o-phenylenediamine and phenylhydrazone derivatives 8a-c in good yields. A one-pot two-component synthesis of tricyclic pyrano[2,3-b]quinoxalines with a pendant hydr
Hydrogen-Bonding Network Anchors the Cyclic Form of Sugar Arylhydrazones
Goldschmidt G?z, Viktória,Pintér, István,Csámpai, Antal,Jákli, Imre,Zsoldos-Mády, Virág,Perczel, András
supporting information, p. 3419 - 3426 (2016/07/23)
The “classical” challenge, raised by Emil Fischer as to why one monosaccharide arylhydrazone adopts a cyclic structure but another an acyclic structure, is answered here. The present comprehensive analysis of hexose and hexosamine arylhydrazones, based on 2D NMR spectroscopy and theoretical modeling, has established that the chain of hydrogen bonds needed for conformational selection can only be completed for d-glucosamine derivatives. Thus, d-glucosamine 4-nitrophenylhydrazone exclusively adopts its cyclic form, but any configurational changes imply the formation of acyclic structures. In conclusion, three criteria dominate structure selection, namely 1) an amino function at the C-2 position, 2) the “all-equatorial” substitution mode of the pyranoid ring, and 3) an electron-withdrawing group on the arylhydrazone are all needed to get the cyclic form only.
