On February 6, 2008, Zhu, Guang; Pang, Keliang; Parkin, Gerard published an article.Safety of 5,6,7,8-Tetrahydroquinoxaline The title of the article was New modes for coordination of aromatic heterocyclic nitrogen compounds to molybdenum: catalytic hydrogenation of quinoline, isoquinoline, and quinoxaline by Mo(PMe3)4H4. And the article contained the following:
The heterocyclic nitrogen compounds (NHetH), isoquinoline (iQH), quinoxaline (QoxH) and quinazoline (QazH), react with Mo(PMe3)6 to give (η2-NHet)Mo(PMe3)4H as a result of cleavage of the C-H bond adjacent to the nitrogen atom. The C-H bond cleavage is reversible, the excess of PMe3 yields the starting compounds back. Furthermore, at elevated temperatures (η2-NHet)Mo(PMe3)4H converts sequentially to isomers of (η6-C,N-NHetH)Mo(PMe3)3 in which the ligand coordinates via the heterocycle, and further, by a haptotropic shift, to (η6-C6-NHetH)Mo(PMe3)3 with coordination via the carbocyclic ring. Isomers of (η6-C,N-NHetH)Mo(PMe3)3 in which the heterocyclic ring coordinated to molybdenum may be hydrogenated, yielding the 1,2,3,4-tetrahydro-derivatives Thus, (η6-C5N-iQH)Mo(PMe3)3 and (η6-C4N2-QoxH)Mo(PMe3)3 react with H2 at 90° to give Mo(PMe3)4H4 and release 1,2,3,4-tetrahydroisoquinoline and 1,2,3,4-tetrahydroquinoxaline, resp. Furthermore, Mo(PMe3)4H4 serves as a catalyst precursor for the hydrogenation of quinoline, isoquinoline, and quinoxaline to the corresponding 1,2,3,4-tetrahydro-heterocycles. The Mo(PMe3)4H4 is the first simple molybdenum complex to effect catalytic hydrogenation of these heterocyclic nitrogen compounds, a necessary step in hydrodenitrogenation. The experimental process involved the reaction of 5,6,7,8-Tetrahydroquinoxaline(cas: 34413-35-9).Safety of 5,6,7,8-Tetrahydroquinoxaline
The Article related to molybdenum trimethylphosphine isoquinoline quinoxaline quinazoline complex preparation haptotropic rearrangement, hydrogenation partial isoquinoline quinoxaline quinazoline molybdenum trimethylphosphine complex and other aspects.Safety of 5,6,7,8-Tetrahydroquinoxaline
Referemce:
Quinoxaline – Wikipedia,
Quinoxaline | C8H6N2 | ChemSpider