Pyrazines, hexahydro

Imidazo[l,5-a]pyrazine, hexahydro-synthesis, 5, 644-645 Imidazo[l,5-a]pyrazine, 3-methyl-Mannich reaction, 5, 625 Imidazo[l,5-a]pyrazine, 3-(methylthio)-reactions... 

PYRAZINE HEXAHYDRIDE or PYRAZINE, HEXAHYDRO- (110-85-0) Combustible solid (flash point 190°F/88°C). Dust or powder forms explosive mixture with air. Violent or explosive reaction with strong oxidizers, strong acids, dicyanofurazan,... 

Structure of 4//-pyrido[l,2-a]pyrazines 348-350 was confirmed by X-ray investigations (99JPR332). The stereostructure of 1,3,4,6,1 l,lla-hexahydro-2/f-pyrazino[l,2-A]isoquinoline-l,4-dione 351 was determined by X-ray investigation (01TL543). 

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). 

Reduction of a 7-(2-oxoethyl) derivative with NaBH4 in EtOH at room temperature gave 7-(2-hydroxyethyl)-2-(2-pyrimidinyl)perhydropyrido[l, 2-u]pyrazine (99MIP6). Reduction of 7-formyl-8-[(4-cyanophenyl)methoxy]-1,3,4,6,11,1 lu-hexahydro-2//-pyrazino[l,2-A]isoquinoline-l,4-dione with NaBH4 yielded a 7-hydroxymethyl derivative (98MIP7). 

Hydroxy group of 8-hyd oxy-2-cycloalkyl-2,3,4,6,ll,lla-hexahydro-l//-pyrazino[l,2-i]isoquinoline-l,4-diones was alkylated with allyl bromide, 2-(bromodifluoromethyl)pyridines, l-(bromodifluoromethyl)- and l-(bro-momethyl)benzenes, halomethyl derivatives of different heterocycles (pyridine, pyrazine, pyrazole, pyrrole, thiazole, thiophene) in the presence of CS2CO3 or K2CO3 (98MIP7). Hydroxy group of 8-hydroxy-2-cyclopentyl-... 

Cyclization of 1 -(9-fluorenylmethoxycarbonyl)-2-[(A-methoxycarbonyl-methyl)aminocarbonyl)piperidine and 2-(9-fluorenylmethoxycarbonyl) -3-[(A-methoxycarbonylmethyl)aminocarbonyl]-1,2,3,4-tetrahydroisoquino-lines on the action of piperidine in THF yielded 2-(l,4-dioxoperhydropyr-ido[ 1,2-fl]pyrazin-2-y 1)- and 2-( 1,4-dioxo-1,3,4,6,11,11 a-hexahydro-2//-pyr-azino[l,2-i]isoquinolin-2-yl)acetamides, respectively (99MIP11). 

Cyclization of (25)-2-(rerc-butoxycarbonylaminomethyl)-l-(2-chloro-acetyl)piperidine on the action of NaH in THF gave (9aS)-2-(rerc-butoxycarbonyl)perhydropyrido[l,2-a]pyrazin-4-one (99H(51)2065). 3-Benzyl-2,3,4,4 ,5,6-hexahydro-l//-pyrazino[l,2-a]quinolin-l-ones 413... 

Azobenzol liefert in Gegenwart von Bernsteinsaure-dichlorid in guter Ausbeute 3,6-Dioxo-1,2-diphenyl-hexahydro-pyrazin (49% d. Th.)s ... 

Stereostructures of a co-crystal of (li )-l- 4-[(9aA)-perhydropyrido[l,2- ]pyrazin-2-yl]phenyl -2-phenyl-7-hydroxy-l, 2,3,4-tetrahydroisoquinoline with ERa-LBD301-553/C — S triple mutant <2005JME364> and iV-[2-(4-hydroxyphenyl)ethyl]-a-propyl-3-[(4-hydroxyphenyl)methyl]-l,4-dioxo-l,2,3,4,ll,l la-hexahydro-67/-pyrazino[l,2- ]isoquinoline-3-acetamide with fructose-1,6-biphosphatase <2003JBC51176> were determined by X-ray crystallography. The structure of a complex formed from 3-[( -methylphenyl)amino]-4-[(4-methylphenyl)imino]-4//-pyrido[l,2-tf]pyrazine with sodium bis(trimethylsilyl)amide and (norbornadiene)Mo(CO)4 in THF was characterized by single crystal X-ray diffraction <1995JPR38>. 

Structures of 3-[(4-methylphenyl)amino]-47/-pyrido[l,2-tf]pyrazine-4-thione, iV-tosyl-3-[(4-methylphenyl)a-mino]-4//-pyrido[l,2-tf]pyrazine 4-imine, and 246 were confirmed by X-ray investigations <1999JPR332>. The stereostructures of (4A,llaA)-lla-ethoxycarbonylT,3,4,6,lla-hexahydro-l,3,4,6,ll,lla-hexahydro-4-methox-ycarbonyl-l-oxo-[l,4]oxazino[4,3-A isoquinoline <1995ZK787>, 2//-pyrazino[l,2- ]isoquinolinc-l,4-dione 247 <2001TL543>, 4-benzyl-2-methyl-1,3,4,6,7,11 b-hcxahydro-2//-pyrazino[2,l -zz] isoqu incline-3,6-dione... 

---