7191-91-5Relevant academic research and scientific papers
Synthesis of 2-aminoquinoxalines via one-pot cyanide-based sequential reaction under aerobic oxidation conditions
Cho, Yeon-Ho,Kim, Kyung-Hee,Cheon, Cheol-Hong
, p. 901 - 907 (2014/03/21)
A highly efficient synthesis of 2-aminoquinoxalines has been developed via the one-pot two-step cyanide-mediated sequential reactions of ortho-phenylenediamines with aldehydes under aerobic oxidation conditions. A variety of substrates, including aliphati
Hydrogen-bond-driven electrophilic activation for selectivity control: Scope and limitations of fluorous alcohol-promoted selective formation of 1,2-disubstituted benzimidazoles and mechanistic insight for rationale of selectivity
Chebolu, Rajesh,Kommi, Damodara N.,Kumar, Dinesh,Bollineni, Narendra,Chakraborti, Asit K.
supporting information, p. 10158 - 10167 (2013/01/15)
Hydrogen-bond-driven electrophilic activation for selectivity control during competitive formation of 1,2-disubstituted and 2-substituted benzimidazoles from o-phenylenediamine and aldehydes is reported. The fluorous alcohols trifluoroethanol and hexafluoro-2-propanol efficiently promote the cyclocondensation of o-phenylenediamine with aldehydes to afford selectively the 1,2-disubstituted benzimidazoles at rt in short times. A mechanistic insight is invoked by NMR, mass spectrometry, and chemical studies to rationalize the selectivity. The ability of the fluorous alcohols in promoting the reaction and controlling the selectivity can be envisaged from their better hydrogen bond donor (HBD) abilities compared to that of the other organic solvents as well as of water. Due to the better HBD values, the fluorous alcohols efficiently promote the initial bisimine formation by electrophilic activation of the aldehyde carbonyl. Subsequently the hydrogen-bond-mediated activation of the in situ-formed bisimine triggers the rearrangement via 1,3-hydride shift to form the 1,2-disubstituted benzimidazoles.
