7- perhydro pyrazine

Oxazolo[4,3-c][l,4]oxazine, perhydro-conformation, 6, 662 Oxazolo[2,3-h]oxazoles synthesis, 6, 989 Oxazolophanes synthesis, 7, 774 (3,5)Oxazolophanes synthesis, 7, 770 5ff-Oxazolo[3,2-a]pyrazine synthesis, 6, 664 5f/-Oxazolo[3,2-6]pyridazine synthesis... 

Racemic or optically active perhydropyrido[l,2-a]pyrazines were obtained by reduction of 9a5-perhydropyrido[l,2-u]pyrazin-4-one with LAH in Et20 at room temperature (99H(51)2065) and by reduction of perhydropyr-ido[l,2-u]pyrazine-l,4-diones with LAH in boiling THF (97USP5703072, 00JAP(K)00/86659). Treatment of (9uS)-2-(fcrf-butoxycarbonyl)perhydro-pyrido[l,2-u]pyrazin-4-one with LAH in Lt20 afforded (9uS)-2-fcrf-butox-ycarbonyl-l,6,7,8,9,9a-hexahydro-2//-pyrido[l,2-a]pyrazine (99H(51)2065). 

Triisopropylsilyl group of 2-[l-triisopropylsilyl-l//-indol-6-yl)perhydro-pyrido[l,2-u]pyrazine was removed by treatment with BU4NF in THF (01MIP5). 

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... 

Hexahydro-l//-pyrido[l,2-a]pyrazin-l-ones were prepared by oxidation of 2-substituted perhydropyrido[l,2-a]pyrazines and perhydro-pyrido[l,2-a]pyrazin-l-one with Hg(OAc)2 in 5% aqueous AcOH (73CPB1248). Oxidation of l,3,4,6,ll,lla-hexahydro-2//-pyrazino[l,2-bjisoquinoline with Hg(OAc)2 in 5% aqueous AcOH gave the 6-oxo derivative [73CPB2039 77IJC(B)70]. l,3,4,6,ll,lla-Hexahydro-2//-... 

Pyrazinecarboxylic acid gave l-benzyl-4-methyl-6-[C-(pyrazin-2-yl)for-mamido]perhydro-1,4-diazepine (41) (1 -benzyl-4-methylperhydro-1,4-di-... 

One of the few examples of formation of the pyrazine ring as the last step in the synthesis of imidazo[4,5-fe]pyrazines (504) involves the reaction of biacetyl with the diamine (503) generated in situ from the 4-nitro-5-amino compound (502) (70TL1013>. Another synthesis involving the use of an imidazole is the condensation of ethylenediamine (505) with (506) to give the perhydro derivative (507). 

Photochemical oxidation of cyclo-DL-Pro-Gly gives peroxide 372 (78CB361). Deprotection of the thiol group of 373 gives the perhydro-pyrrolo[l,2-a]pyrazin-l,4-dione (374) (85TL5481). 

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