6-Hydroxy-3,4-dihydro-2 pyrazinone

A general type of [3 + 3] heterocyclization involves initial nucleophilic attack on the electrophilic three-membered heterocycle by a 1,3-electrophile-nucleophile. Aziridines (330) with either a-mercapto ketones (329) or with a mixture of a ketone and sulfur give 5,6-dihydro-1,4-thiazines (330 — 331 — 332). Azirines (333) can be used for the preparation of pyrazinones (334) from ot-amino esters R2CH(NH2)C02Et and of 1,4-oxazinones from a-hydroxy esters (83TL1153). [Pg.584]

Af-Benzyl-/V- (/V-o-methoxyphcnylcarbamoyl)mcthyl glycine (29) underwent de-hydrative cyclization to 4-benzyl-6-hydroxy-l-o-methoxyphenyl-3,4-dihydro-2(1 H)- pyrazinone (30) (l,r-carbonyldiimidazole, THF, 30 —> 65°C, 17 h 83% other reagents gave lower yields).487... [Pg.7]

Iminodipropiononitrile (53) gave 6-hydroxy-3,5-dimethyl-3,4-dihydro-2(l//)-pyrazinone (54) (HCl/EtOH, 0°C, 12 h then Na2C03—H20 18% by a yet unconfirmed mechanism).577 Also other examples 436 747,749,1180,1284... [Pg.10]

V-(l-Acetyl-l-methylethyl)-2-chloro-(V-hydroxyacetamide (69) gave 1-hydroxy-5,6,6-(rimc(hyl-3,6-dihydro-2( I //(-pyrazinone (70) (NH4OH—I (OH—dioxane, 20°C, 3 days 8%) likewise one homologue.424 Aldehydes gave better results under reductive conditions.1768... [Pg.12]

Bis(carboxymethyl)amine (84, R = H) gave 4-formyl-6-hydroxy-3,4-dihydro-2( I //)-pyrazinone (83, Q = CHO) [HC02NH4, Me2NCHO—PhMe, Dean-Stark H20 removal, 150-170°C (bath ), 4 h 58%], and thence... [Pg.14]

Hydroxy-4-methyl-3,4-dihydro-2(l//)-pyrazinone (101) gave 1-methylpiper-azine (102) (LiAlHa, THF, 20 C. reflux, 4 h ... [Pg.206]

Dihydro-6-hydroxy-6- hydroxyphenylmethyl)-3,5-dimethoxy-3- l-methylethyl)-2 lY )-pyrazinone, 9C1 [165306-63-8]... [Pg.361]

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