Synthesis of Pyrano[4,3-<i>c</i>]pyrazol-4(1<i>H</i>)-ones and -4(2<i>H</i>)-ones from Dehydroacetic Acid. Homo- and Heteronuclear Selective NOE Measurements for Unambiguous Structure Assignment
作者:Albert Cantos、Pedro de March、Marcial Moreno-Mañas、Anna Pla、Francisco Sanchez-Ferrando、Albert Virgili
DOI:10.1246/bcsj.60.4425
日期:1987.12
Cyclization of dehydroacetic acid N-substituted hydrazones furnished 1-substituted 3,6-dimethylpyrano[4,3-c]pyrazol-4(1H)-ones, together with varying amounts of N,N′-disubstituted 5-hydroxy-3-methyl-4-(3-methyl-1H-pyrazol-5-yl)-1H-pyrazoles. The same pyranopyrazolones were obtained regioselectively without side reactions from N-alkylhydrazines and 4-chloro-3-(1-chlorovinyl)-6-methyl-2H-pyran-2-one
脱氢乙酸 N-取代腙环化得到 1-取代 3,6-二甲基吡喃并[4,3-c]吡唑-4(1H)-酮,以及不同数量的 N,N'-二取代 5-羟基-3-甲基-4-(3-甲基-1H-吡唑-5-基)-1H-吡唑。N-烷基肼和 4-氯-3-(1-氯乙烯基)-6-甲基-2H-吡喃-2-酮(“脱氢乙酰氯”)在没有副反应的情况下区域选择性地获得了相同的吡喃并吡唑啉酮,而 N-芳基肼得到了2-芳基-3,6-二甲基吡喃并[4,3-c]吡唑-4(2H)-酮。NMR NOE 方法,包括远程选择性异核 13C1H}NOE 增强测量,允许明确区分 -4(1H)-ones 和 -4(2H)-ones。