Synthesis of α-(Pentafluorosulfanyl)- and α-(Trifluoromethyl)-Substituted Carboxylic Acid Derivatives by Ireland–Claisen Rearrangement
作者:Anna-Lena Dreier、Bernd Beutel、Christian Mück-Lichtenfeld、Andrej V. Matsnev、Joseph S. Thrasher、Günter Haufe
DOI:10.1021/acs.joc.6b02805
日期:2017.2.3
by trimethylsilyl triflate (TMSOTf). This Ireland–Claisen rearrangement delivered approximate 1:1 mixtures of syn/anti diastereoisomers due to tiny differences (<0.5 kcal/mol) both in the energy of (Z)/(E)-isomeric ester enolates and in the alternative Zimmerman–Traxler transition states of model compounds as shown by DFT calculations. Acidic reaction conditions have to be avoided since addition of the
较早的研究表明,烯丙基酯的[3,3]-σ重排可用于构建含氟羧酸衍生物。本文介绍了通过处理相应的SF 5-或CF 3-乙酸酯合成在2位带有五氟硫基(SF 5)或三氟甲基(CF 3)取代基的3-芳基-戊-4-烯酸衍生物。的p -取代的肉桂基醇与三乙胺,接着三甲基硅烷基三氟甲磺酸酯酯(TMSOTf)。由于(Z)/(E)异构酯烯酸酯,以及模型化合物的替代Zimmerman-Traxler过渡态,如DFT计算所示。必须避免酸性反应条件,因为以相反的顺序添加试剂(首先是TMSOTf,然后是Et 3 N)会导致肉桂基SF 5-和CF 3-乙酸酯低聚。在后一种条件下处理相应的区域异构的乙酸1-苯基-丙-2-烯-1-基乙酸酯导致[1,3]-σ重排和随后形成的肉桂酸酯的低聚。当首先添加Et 3 N,然后添加TMSOTf时,未检测到形成的酯的进一步反应。