1- Benzyl-2 -pyrazinone 4-oxide

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... 

Benzyl-6-methyl-2(177)-pyrazinone 3-Benzyl-5-mcthyl-2(l //)-pyrazinone 6-Benzyl-5-mothy 1-2(1 //)-pyrazinone 1 -Benzyl-6-oxo-l, 6-dihydro-2-pyrazine-carboxylic acid 4-oxide... 

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