Hypervalent iodine oxidation of 5-substituted and 4,5-disubstituted pyrazol-3(2H)-ones: A facile synthesis of methyl-2-alkynoates and methyl 2,3-alkadienoates
作者:R.M. Moriarty、R.K. Vaid、V.T. Ravikumar、T.E. Hopkins、P. Farid
DOI:10.1016/s0040-4020(01)80023-5
日期:1989.1
Hypervalent iodine oxidation of various 5-substituted pyrazol-3(2H)-ones (1a-h) with iodobenzene diacetate or iodosobenzene in methanol results in fragmentative loss of molecular dinitrogen to yield methyl 2-alkynoates (2a-h). However, 5-methyl-4-substituted pyrazol-3(2H)-ones (3a-d) under similar conditions yield methyl 2,3-allenic esters (4a-d). Methyl 2,3-cycloalkadienoates (6a-e) are obtained by
用甲醇中的碘代苯二乙酸酯或碘代苯在甲醇中对各种5-取代的吡唑-3(2 H)-ones(1 a-h)进行高价碘氧化,会导致分子中的二氮分子碎裂性损失,从而生成2-炔酸甲酯(2 a-h)。然而,在相似条件下,由5-甲基-4-取代的吡唑-3(2 H)-ones(3 a-d)产生甲基2,3-丙二酸酯(4 a-d)。甲基-2,3- cycloalkadienoates(6 A-E)是由4,5-聚吡唑-3(2的氧化裂解得到ħ) -酮(5 C-E)用二乙酸碘苯或亚碘酰苯甲醇中。5-甲基-4,4-二取代吡唑-3(2 H)-ones(发现7a -b)在相似条件下不发生反应。讨论了这些反应的范围和机理。