- A Photochemical Ring Contraction of an Imino Lactam
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The photochemical rearrangement of three tetrahydro-2-pyrazinones in aqueous medium to imidazol-5-ones is described. 1,2,5,6-Tetrahydro-3,5,5-trimethyl-2-pyrazinone (4) gives 1,2,2,4-tetramethyl-3-imidazolin-5-one (7), 1,2,5,6-tetrahydro-3,6,6-trimethyl-2-pyrazinone (5) gives 4-methyl-5-imidazolidinone (9), and 1,2,5,6-tetrahydro-1,3,5,5-tetramethyl-2-pyrazinone (6) gives 1,4-dimethyl-5-imidazolidinone (8).A mechanism involving enediimine and isoimidazole intermediates is proposed in analogy with the mechanism for rearrangement of 5,6-dihydropyrazines to imidazoles.
- Kleyer, Don L.,Koch, Tad H.
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p. 3145 - 3148
(2007/10/02)
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