New Flexible Synthesis of Pyrazoles with Different, Functionalized Substituents at C3 and C5
作者:Douglas B. Grotjahn、Sang Van、David Combs、Daniel A. Lev、Christian Schneider、Marc Rideout、Christoph Meyer、Genaro Hernandez、Lupe Mejorado
DOI:10.1021/jo026083e
日期:2002.12.1
presented. Installation of R = methyl, isopropyl, tert-butyl, adamantyl, or phenyl groups at C5 is reported here, starting by coupling protected alkynols with acid chlorides RCOCl, forming alkynyl ketones, which are reacted with hydrazine to form the pyrazole nucleus. Alcohol deprotection and conversion to a chloride gave 5-substituted 3-(chloromethyl)- or 3-(2-chloroethyl)pyrazoles. This sequence can be
呈现了具有连接至碳3的官能化侧链和连接至碳5的变化的烷基和芳基取代基的吡唑的合成。此处报道了在C5处安装R =甲基,异丙基,叔丁基,金刚烷基或苯基,方法是首先将受保护的炔醇与酰氯RCOCl偶联,形成炔基酮,然后与肼反应形成吡唑核。醇脱保护并转化为氯化物,得到5-取代的3-(氯甲基)-或3-(2-氯乙基)吡唑。此序列可以在2 d内以30 g的规模完成,并具有出色的总产量。通过亲核取代反应,氯化物是其他多官能吡唑的有用前体。在本文的工作中,制备了在C3上具有侧链LCH(2)-和LCH(2)CH(2)-的衍生物(L =硫醚或膦)作为配体。