Pyrido pyrazine-7-carboxylates

H-Pyrido[2,l-i]purine-9-carboxylic acid, 7-oxo-methyl ester, 5, 566 Pyrido[2,3-6]pyrazine, amino-nucleophilic attack, 3, 253 Pyrido[2,3-h]pyrazine, 6-chloro-reactions... 

Pyrido[2,3-b]pyrazin-8-one-7-carboxylic acids H NMR, 3, 249 Pyrido[2,3-b]pyrazinones alkylation, 3, 250... 

Amine bound to a Wang-polystyrene resin 381 was acylated with 4-oxo-4Ff-pyrido[l,2-u]pyrazine-3-carboxylic acid in the presence of bromotrispyrrolidinophosphonium hexafluorophosphate and /-Pr2NEt in A-methylpyrrolidone (98MIP16). l-(4-Cyclohexyl-4-r / r-butylaminocarbo-nyl-l-piperidyl)-2-(4-fluorophenyl)ethylamine was acylated with perhydro-pyrido[l,2-u]pyrazine-3-carboxylic acid (01MIP19). An amino group of a macrocyclic compound attached to a solid support was acylated with... 

Two examples were reported for the synthesis of the pyrido[2,3-, ]pyrazine moiety using pyrazine precursors. Thus, amidation of methyl 2-aminopyrazine-3-carboxylate 670 with a substituted acetyl chloride followed by heterocycliza-tion of the formed amide 671 gave 6,8-dihydroxy pyridopyrazine 672 <2004W02004056825>. 

Pyrazine 168 underwent cross-coupling with propyne in the tri-o-tolylphosphine, and copper(l) iodide to provide 170. The isocyanate or methyl chloroformate and sodium hydride to give An isolated example of the synthesis of chiral pteridines from a (Scheme 33). 2-Isothiocyanatopyrazine-3-carboxylates have been isothiocyanatopyrazine-2-carboxylate 172 reacted with R)- —) provided the pteridine derivative 173 and uncyclized pyrazine with pyridine precursors afforded pyrido[2,3 Pytitnidines. 

Oxidation of 3-hydroxymethyl-2,3-dihydro-5H-pyrido[l,2,3-cfe][1,4] benzoxazin-5-ones with o-iodoxybenzoic acid in DMSO and with Dess-Martin periodinate in CH2CI2 afforded 3-formyl derivatives (08WOP2008/ 120003). Dehydrogenation of ethyl 10-[2-(ferf-butoxycarbonyl)-l,2,3,4,6,8a-hexahydropyrrolo[l,2-a]pyrazin-7-yl]-9-fluoro-3(S)-methyl-7-oxo-2,3-dihydro-7H-pyrido[l,2,3-de][l,4]oxazine-6-carboxylates in the presence of Pd/C with air in MeOH afforded 10-[2-(ferf-butoxycarbonyl)-l, 2,3,4-tetrahydropyrrolo[l,2-a]pyrazin-7-yl] derivatives, which then were deprotected (09BML4933). 

Reduction of cis-6H,9aH-, 4-d ioxoperhyd ropyridoLl, 2-aJpyrazine-6-carboxylate with LAH yielded quantitatively 6-hydroxymethylperhydro-pyrido[l,2-a]pyrazine (07USA2007/037816, 07USA2007/037817). 

Reaction of l-(2-oxoethyl)-4-oxo-l,4-dihydropyridine-2-carboxylate 418 and 2-methoxyethylamine in the presence of AcOH at 140 °C for 0.5 h under microwave irradiation provided l,2-dihydro-8H-pyrido[l,2-a pyrazine-1,8-dione 419 (06WOP2006/088173, 07WOP2007/049675). 

Reactions of y-chloropropylamines HC1 471 and acetylene compound 472 in MeCN in the presence of a base, 4 A MS and BU4NI afforded 3-oxo-3,4,7,8-tetrahydro-lH,6H-pyrido[2,l -c] [1,4]oxazine-9-carboxylates 473 (06T5697). Similar reactions of acetylene derivatives 474 provided 3-oxo-3,4,7,8-tetrahydro-lH,6H-pyrido[2,l-a]pyrazine-9-carboxylates 475. 

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