A REGIOSELECTIVE SYNTHESIS OF METHYL 7-AMINO-3-PHENYLTHIENO-[2,3-b]PYRAZINE-6-CARBOXYLATE

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“…Scheme 13. Reaction of 2,3-diamino-3-phenylthioacrylonitrile with 2,2-diethoxyacetophenone reported by Zhang et al (2001). (Kong et al, 2012).…”

“…Seven years later, Zhang et al (2001) repeated the above reaction using phenylglyoxal and found that the product was a mixture of 5phenyl-3-phenylthiopyrazine-carbonitrile and 6phenyl-3-phenylthio-pyrazinecarbonitrile without any selectivity. Thus, instead of phenylglyoxal, Zhang et al (2001) utilized 2,2diethoxyacetophenone to react with 2,3diamino-3-phenylthio-acrylonitrile to give a similar mixture (Scheme 13). High selectivity of 6-phenyl-3-phenylthio-pyrazinecarbonitrile could be produced in a good yield (86%) from the reaction with the presence of excess trifluoroacetic acid (TFA).…”

Arylglyoxals in Synthesis of Heterocyclic Compounds

“…Zhang et al reported the regioselective condensation reaction of 2,3-diamino-3-phenylthioacrylonitrile 487 with PG-acetal to produce 3-cyano-5-phenyl-3-phenylthiopyrazine 488a . When reaction was conducted in i -PrOH in the presence of excess TFA, 488a was obtained in high selectivity.…”

“…532 The preparation of 2-amino-3-methyl-6-phenylpyrazine 1oxide 481, a model for structural elucidation of Cypridina etioluciferamine, was developed by Karpetsky et al 533 Condensation of p-methoxyphenylglyoxal with 2,3-diaminopropionic acid hydrobromide 482 to synthesize pyrazine carboxylic acid 483 in methanolic NaOH solution was the first step of the synthesis of botryllazine B 484, a naturally occurring alkaloid that was first isolated from the red ascidian Botryllus leachi (Scheme 138). 186 Vogl and Taylor 534 Zhang et al 535 reported the regioselective condensation reaction of 2,3-diamino-3-phenylthioacrylonitrile 487 with PGacetal to produce 3-cyano-5-phenyl-3-phenylthiopyrazine 488a. When reaction was conducted in i-PrOH in the presence of excess TFA, 488a was obtained in high selectivity.…”