| Research Abstract |
Five 2-aryl-3-(3-methyl-5-isoxazolyl)-N-silyl-1-aza-allyl anions (1) (Ar = C_6H_5, pーCH_3C_6H_4, p-CH_3OC_6H_4, p-CIC_6H_4, p-N(CH_3) _2C_6H_4), generated from 3-methyl-5-(trimethylsilylmethyl) isoxazole and the corresponding aryl cyanides, reacted with perfluoro (2-methyl-2-pentene) (2) in the presence of Hunig's base in tetrahydrofuran at low temperature to give the corresponding 6-aryl-2-fluoro-5-(3-methyl-5-isoxazolyl)-4-pentafluoroethyl-3-trifluoromethylpyridines (3) in high yields (97, 74, 52, 80, 93%, respectively) under the optimized reaction conditions. Further-more, the isoxazole ring of the pyridine (3) was quantitatively hydrogenated to afford the corresponding bata-amion enone (4), which was intramolecularly cyclized to give 5-ary1-7-fluoro-2-methyl-8-trifluoromethyl-1, 4-dihydro-1, 6-naphthyridine (5) in good yields (Ar = C_6H_5, p-CIC_6H_5, yield = 63, 67%, respectively) in the presence of sodium hydroxide at room temperature. The mechanisms for these two reaction were also discussed on the basis of the reactivity of (3) against sodium hydroxide or alkylamines.
alpha-(Trimethylsilylmethyl)-N-heterocycles, such as pyridine, quinoline, and isoquinoline, reacted with (2) in the presence of fluoride anion to afford Rf-substituted quinolizin-4-ones (or the corresponding benzo derivatives) in poor to good yields through intermolecular addition-cyclization reaction.
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