Pyrido pyrazine scaffolds

Baron, A., Sandford, G., Slater, R., et al. (2005) Polyfunctional tetrahydro-pyrido[2,3b]pyrazine scaffolds from 4-phenylsulfonyl-tetrafluoropyridine. J. Org. Chem., 70, 9377-9381. 

Lindsley and co-workers developed a general procedure towards the collection of diverse heterocyclic scaffolds from common 1,2-diketone intermediates 96. Substituted quinoxalines 97, fused pyrazolo [ 4,5-g ] quinoxalines 98 and imidazolo[3,4-g]quinoxalines 99 as well as pyrido[2,3-fo]pyrazines 100 and Ihicno[3,4-fo Ipyrazincs 101 have been prepared in excellent yields [132] (Scheme 54), employing optimized reaction conditions (microwave heating of equimolar mixtures of 1,2-diketone 96 and diamine components at 160 °C for 5 min in 9 1 MeOH - AcOH). The use of microwave irradiation resulted in reduced reaction times (5 min vs. 2-12 hours), improved yields as well as the suppressed formation of polymeric species a characteristic of traditional... 

Table 11.5 Synthesis of pyrido[3,4-b]pyrazine and imidazopyridine scaffolds [47, 56]... 

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