REACTIVITY OF BIOLOGICALLY IMPORTANT REDUCED PYRIDINES .4. EFFECT OF SUBSTITUTION ON FERRICYANIDE-MEDIATED OXIDATION RATES OF VARIOUS 1,4-DIHYDROPYRIDINES
REACTIVITY OF BIOLOGICALLY IMPORTANT REDUCED PYRIDINES .4. EFFECT OF SUBSTITUTION ON FERRICYANIDE-MEDIATED OXIDATION RATES OF VARIOUS 1,4-DIHYDROPYRIDINES
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DOI：
10.1021/jo00276a039
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发表时间：
1989-07-21
影响因子：
3.6
通讯作者：
BODOR, N
中科院分区：
文献类型：
--
作者：
BREWSTER, ME;SIMAY, A;BODOR, N
研究了取代对铁氰化物介导的各种二氢吡啶氧化速率的影响。对1-烷基-、1-芳烷基-、1-芳基-和6-取代的1-甲基-1，4-二氢烟酰胺、3-取代的1-甲基-1，4-二氢吡啶、喹啉和异喹啉衍生物进行铁氰化物氧化。增加1-甲基-1，4-二氢烟酰胺的正烷基链起到缓慢降低氧化速率的作用。与1-异丙基衍生物相比，1-环丙基-1，4-二氢烟酰胺显示出异常稳定，这可能是由于π-的吸电子性质类似取代基。1-（4-取代的苯基）-1，4-二氢烟酰胺在p-NO2（σ）范围内= 0.778）至p-N（CH 3）2（σ= 0.83）产生线性Hammett图（r = 0.9994），反应常数为ρ。= 2.76，与氧化的速率决定步骤中的初始电子去除一致。当考虑在3位的取代时，稳定性的等级顺序为CHO > CN > COCH 3> COOCH 3> CONH 2> CONHR > CONR 2，并且与该部分的吸电子效力有关。最后发现1-甲基-1，4-二氢-3-喹啉甲酰胺比2-甲基-1，2-二氢-4-异喹啉甲酰胺稳定得多。
The effect of substitution on the rate of ferricyanide-mediated oxidation of various dihydropyridines was examined. 1-Alkyl-, 1-aralkyl-, 1-aryl-, and 6-substituted 1-methyl-1,4-dihydronicotinamides, 3-substituted 1-methyl-1,4-dihydropyridines, and quinoline and isoquinoline derivatives were subjected to ferricyanide oxidation. Increasing the n-alkyl chain of 1-methyl-1,4-dihydronicotinamide acted to slowly decrease the rate of oxidation. The 1-cyclopropyl-1,4-dihydronicotinamide was shown to be unusually stable compared to the 1-isopropyl derivative due presumably to the electron-withdrawing nature of the .pi.-like substituent. 1-(4-Substituted phenyl)-1,4-dihydronicotinamides over the range of p-NO2 (.sigma. = 0.778) to p-N(CH3)2 (.sigma. = 0.83) generated a linear Hammett plot (r = 0.9994) with a reaction constant of .rho. = 2.76, consistent with an initial electron removal in the rate-determining step of oxidation. When substitutions at the 3-position are considered, the rank order of stability was CHO > CN > COCH3 > COOCH3 > CONH2 > CONHR > CONR2 and is related to the electron-withdrawing potency of the moiety. Finally the 1-methyl-1,4-dihydro-3-quinolinecarboxamide was found to be much more stable than the 2-methyl-1,2-dihydro-4-isquinolinecarboxamide.