Pyrazinones, tetrahydro

The cycloadducts formed from the Diels-Alder reaction of 3-amino-5-chloro-2(17/)-pyrazinones with methyl acrylate in toluene are subject to two alternative modes of ring transformation yielding either methyl 6-cyano-l,2-dihydro-2-oxo-4-pyridinecarboxylates or the corresponding 3-amino-6-cyano-l,2,5,6-tetrahydro-2-oxo-4-pyridinecarboxylates. From the latter compounds, 3-amino-2-pyridones can be generated through subsequent loss of HCN <96 JOC(61)304>. Synthesis of 3-spirocyclopropane-4-pyridone and furo[2,3-c]pyridine derivatives can be achieved by the thermal rearrangement of nitrone and nitrile oxide cycloadducts of bicyclopropylidene <96JCX (61)1665>. [Pg.224]

Benzyl-6-[A -(but-3-ynyl)-A -propionylaminomethyl]-5-chloro-3-methoxy-2(l//)-pyrazinone (48) underwent thermolysis to afford l-benzyl-3-methoxy-7-propio-nyl-5,6,7,8-tetrahydro-l,7-naphthyridin-2(l/7)-one (49) (PhBr, reflux, 2 h 53%, after separation from a second product) the proposed intermediate was not isolated.602... [Pg.151]

Benzyloxycarbonylamino)acetamido]-3-hydroxypropionaldehyde hydrate (12) gave 6-hydroxymethyl-3,4,5,6-tetrahydro-2 (I //l-pyrazinone (13) (Pd/C, MeOH, H2) 50 atm, 20°C, 24 h 96%).1061 2-(2-Aminoethylamino)ethanol gave piperazine (14) (Cu—A1203 catalyst, continuous flow, 200°C 95%).1064 Also other examples.1330,1641... [Pg.4]

Af-(2-Aminoethyl)-Ai-carboxymethylglycine (31) gave 4-carboxymethyl-3,4,5, 6-tetrahydro-2(177)-pyrazinone (32) (Me2NCHO, reflux %).820 Also the formation of bis(3,6-dioxopiperazin-2-ylmethyl)disulfide (33)1440 and... [Pg.7]

Methyl A-(2-diallylamino-3-hydroxyhcxyl)-2-isopropylglycinatc (42) gave 6-(l-hydroxybutyl)-3-isopropyl-3,4,5,6-tetrahydro-2(l//)-pyrazinone (43) [(Ph3P)3 RhCl, MeCN—H20, distillation (see original for details), 5 h 47%].404 Also other examples 182,189,229,703,813,843,1347,1465,1495,1498,1535,1750... [Pg.8]

Amino-2-methyl-l-propylaminopropane (148) and acetone cyanohydrin (2-hydroxy-2-methylpropionoitrile 149) gave 3,3,5,5-tetramethyl-l-propyl-3,4,5,6-tetrahydro-2(l/7)-pyrazinone (150, X = 0), presumably via the imine (150, X = NH) (PhCH2Et3NCl, NaOH, CHC13—H20, 5°C, >5 h 70%) also analogues.187... [Pg.23]

The only examples of this synthesis employed isoxazolopyrazine substrates that were themselves made from pyrazines. Thus l-benzyl-5,6-dihydro-2(l//)-pyrazi-none 4-oxide (99) underwent addition by ethynylbenzene to give 5-benzyl-2-phemi-6,7-dihydro-3a//-isoxazolo[2,3-a]pyrazin-4(5//)-onc (100) (60%), which subsequently underwent ring cleavage by molybdenum hexacarbonyl in wet acetonitrile to afford l-benzyl-3-phenacyl-3,4,5,6-tetrahydro-2(l//)-pyrazinone (101) in 54% yield several analogues were made similarly.1539... [Pg.62]

Diethyl-5-methyl-3,6-dihydro-2(l//)-pyrazinone 4-oxide (301) gave dimethyl 4,4-diethyl-3a-methyl-6-oxo-4,5,6,7-tetrahydro-3a/7-isoxazolo[2,3-a]pyrazine-2,3-dicarboxylate (302) (Me02CC CC02Me, CHC13, reflux, 3 h 64%) 544 homologues likewise.544... [Pg.238]

Benzylthio-2(177)-pyrazinone (1) gave 5-thioxo-3,4,5,6-tetrahydro-2(17/)-pyrazinone (3) (Na, liquid NH3, -76°C, 1 h 70%) a small yield of the intermediate 5-mercapto-2( I 7/)-pyrazinone (2) was obtained when the proportion of sodium to substrate was decreased.1565... [Pg.246]

Methyl 2- 2-[ /-(2-bromoethyl)-o-nitrobenzenesulfonamido]propionamido -2-phenylacetate (6) gave l-(a-methoxycarbonylbenzyl)-3-methyl-4-<9-nitroben-zenesulfonyl-3.4.5.6-tetrahydro-2(l//)-pyrazinone (7) [1,8-diazabicyclo [5,4,0]undec-7-ene, tetrahydrofuran(THF) > 95%] ... [Pg.3]

A(-(2-Benzylaminoethyl)cyclohexanecarboxamide (115) and chloroacetyl chloride (116) gave l-benzyl-4-cyclohexylformyl-3,4,5,6-tetrahydro-2(177)-pyrazinone (117) (NaOH, I liClI J. frNCI, 11,0 Phil, 20 55 ( , 2... [Pg.19]

Photochemical rearrangement of tetrahydro-2-pyrazinones to imidazol-5-ones (62%) in aqueous solution is believed to proceed through enediimine and isoimidazole intermediates, in analogy with the mechanism of rearrangement of 5,6-dihydropyrazines to imidazoles <82J0C3145>. [Pg.217]

Conventional methods have been used to prepare ribonucleoside analogues from 2-(l//)pyrazinone, 3,5-disubstituted pyridines (including a-anomers), 6-methyl-l,3-oxazine-2,4-dione and 6-methyluracil, 2-alkyl-4,5-dicarboxamido-imidazoles, 7-membered ring analogues (4) and (5) of uracil and tetrahydro-uracil [one diastereomer of (4) being the most potent inhibitor of cytidine deaminase yet discovered], 2-alkylthioadenine, 8-aza-3-deaza-guanine/ ... [Pg.170]

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