19459-03-1Relevant articles and documents
Enantioselective Synthesis of Chiral Substituted 2,4-Diketoimidazolidines and 2,5-Diketopiperazines via Asymmetric Hydrogenation
Xiao, Guiying,Xu, Shuang,Xie, Chaochao,Zi, Guofu,Ye, Weiping,Zhou, Zhangtao,Hou, Guohua,Zhang, Zhanbin
supporting information, p. 5734 - 5738 (2021/08/01)
An enantioselective hydrogenation of 5-alkylidene-2,4-diketoimidazolidines (hydantoins) and 3-alkylidene-2,5-ketopiperazines catalyzed by the Rh/f-spiroPhos complex under mild conditions has been developed, which provides an efficient approach to the highly enantioselective synthesis of chiral hydantoins and 2,5-ketopiperazine derivatives with high enantioselectivities up to 99.9% ee.
Pyrazine Chemistry. Part 14. On the Preparation and Oxygenation of Pyrazines and Some Reactions of the Product Peroxides
Dawson, Ian M.,Pappin, Amanda J.,Peck, Colin J.,Sammes, Peter G.
, p. 453 - 461 (2007/10/02)
Some new methods for preparing substituted pyrazines are reported. 2,6-Dimethoxy substituted pyrazines undergo facile addition of singlet oxygen to form endoperoxides, some of which are remarkably stable.The behaviour of these compounds has been explored.In particular, deoxygenation is effected with triphenylphosphine to induce skeletal rearrangements, the pyrazines undergoing ring contraction to substituted imidazoles.The rearrangement occurs via intermediate oxadiazepines which can be intercepted by intramolecular trapping with a pendant hydroxy group, leading to a novel method for entry into the 3,6,1-oxadiazepine system.Reductive cleavage of the peroxide bond leads to unstable dihydroxydihydropyrazines.
