The combined use of 2D NMR correlation methods and ab initio chemical shift calcula tions is efficient and, in some cases, virtually the only way to determine the structures of new organic compounds. This approach enabled us to establish the structure of the major unusual product of the three component reaction of imidazo[1,5 a]quinoxalin 4 one, bis(2 chloro ethyl)amine hydrochloride, and potassium carbonate in DMF.
New three-component domino reactions,
providing divergent approaches
to multifunctionalized pyrroles with different substitution patterns,
have been established (47 examples). In this work, a new rearrangement
of quinoxalinones with the participation of the in situ-generated 2-en-1-imine moiety of the substituent at C3 makes it
possible to construct two new heterocyclic systems, namely, a benzimidazolone
and a pyrrole, simultaneously under one-pot reaction conditions. The
reaction is easy to perform simply by mixing three common reactants
of acetic acid with heating. Secondary amines or primary alcohols
as the third component of the reaction, along with quinoxalin-3(4H)-ones and malononitrile, not only initiate the rearrangement
but also are responsible for the nature of substituents at position
5 of the pyrrole ring in the newly formed new biheterocyclic system.
The reaction proceeds smoothly and can be finished within 7 h, which
makes workup convenient to give up to 97% chemical yields.
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