Cycloaddition routes to azaanthraquinone derivatives. 1. Use of azadienophiles

A Survey of Synthetic Routes and Antitumor Activities for Benzo[g]quinoxaline-5,10-diones

“…The synthesis of 6,9- bis -[(aminoalkyl)amino]- substituted benzo[ g ]quinoxalines was described [ 47 , 48 , 49 , 50 , 51 ]. They were prepared by displacements (S N Ar) of the fluorides from 6,9-difluoro- substituted benzo[ g ]quinoxaline.…”

“…Cycloadditions with cyclic dienes are expected to occur with formation of a 1:1-cycloadduct, followed by tautomerization and ready oxidation. This yields a bridged ring system which can undergo thermal elimination of ethylene to afford diazaanthraquinone [ 51 ]. Cycloadditions of 1,3-cyclohexadiene with the other heterocyclic quinones also yielded initial 1:1-cycloadducts 86 , which were isolated directly from the reaction mixture.…”

Preparation and evaluation of a set of bis(methoxycarbonylmethylthio) heteroquinones as CDC25B phosphatase inhibitors

“…Accordingly [33,34] with methyl mercaptoacetate, followed by oxidation (CAN) in a stepwise and duplicated manner (see experimental section), afforded bis-substituted heteroquinones, 22-24, (Figure 2). Concerning the 5,8-quinoxalinequinone scaffold [24,35,36], it yielded a bis-(thio)hydroquinone in a single step which was followed by oxidation to get 25.…”

One Pot and Metal-Free Approach to 3-(2-Hydroxybenzoyl)-1-aza-anthraquinones

“…As far as we know, there are some synthetic routes that have been elaborated to construct 1-aza-anthraquinones, such as Diels–Alder reactions [13,14,15,16], Friedel–Crafts reactions [17,18], Michael-type addition followed by ring expansion [19,20], and 6- exo-trig radical cyclization of N -(2-alkenylaryl)-substituted enamines [21]. Despite the great potential of these methods, the use of toxic metal agents, inconvenient availability of starting materials, as well as poor regioselectivity and low yields of these reactions limited their wide applications.…”