Beilstein J. Org. Chem.2017,13, 428–440, doi:10.3762/bjoc.13.46
; praziquantel; pyrazinoisoquinoline; pyridopyrazine; Introduction
Piperazine is an important structural core found in many biologically active natural products [1]. Piperazines are also useful intermediates in the synthesis of a variety of drug molecules having important biological activities such as
for the synthesis of many alkaloids (Figure 1) [16].
To synthesize pyrazinoisoquinoline and its derivatives, various approaches such as the Ugi multicomponent reaction [17] amidoalkylation [18][19], N-acyliminium ion cyclization [20] and a radical cyclization [21] have been reported. To this end
corresponding products.
Further, these 4-benzenesulfonylpiperazine-2,6-diones were subjected to an imide carbonyl group activation strategy, to develop a practical approach to synthesize pyrazinoisoquinoline and pyridopyrazines via Brønsted acid assisted 6-exo-trig cyclization of arylethylpiperazine-2,6-diones
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Graphical Abstract
Figure 1:
Selected active pyrazinoisoquinolines, 2-oxopiperazines and aldose reductase inhibitors (ALR2).