Asymmetric Conjugate Addition of Grignard Reagents to Pyranones
作者:Bin Mao、Martín Fañanás-Mastral、Ben L. Feringa
DOI:10.1021/ol303141x
日期:2013.1.18
efficient enantioselectivesynthesis of lactones was developed based on the catalyticasymmetricconjugateaddition (ACA) of alkyl Grignard reagents to pyranones. The use of 2H-pyran-2-one for the first time in the ACA with Grignard reagents allows for a variety of further transformations to access highly versatile building blocks such as β-alkyl substituted aldehydes or β-bromo-γ-alkyl substituted alcohols
基于烷基格氏试剂向吡喃酮的催化不对称共轭加成(ACA),开发了内酯的有效对映选择性合成。带有Grignard试剂的ACA中首次使用2 H -pyran-2-one可以进行多种进一步的转化,以得到高度通用的结构单元,例如β-烷基取代的醛或β-溴-γ-烷基取代的具有出色的区域选择性和立体选择性的醇。
Chemo- and Regioselective Synthesis of Acyl-Cyclohexenes by a Tandem Acceptorless Dehydrogenation-[1,5]-Hydride Shift Cascade
作者:Lewis B. Smith、Roly J. Armstrong、Daniel Matheau-Raven、Timothy J. Donohoe
DOI:10.1021/jacs.9b12296
日期:2020.2.5
acceptorless dehydrogenation of the diol followed by a redox-neutral cascade process, which is independent of the iridium catalyst. Deuteriumlabelingstudies established that the key step of this cascade involves a novel base-mediated [1,5]-hydride shift. The cyclohexenyl ketone products could readily be cleaved under mildly acidic conditions to access a range of valuable substituted cyclohexene derivatives
描述了一种从五甲基苯乙酮和 1,5-二醇中获得取代的酰基环己烯的原子经济方法。该过程由铱 (I) 催化剂与庞大的富电子膦配体 (CataCXium A) 共同催化,该配体有利于无受体脱氢反应,而不是共轭还原成相应的环己烷。该反应产生水和氢气作为唯一的副产物,并且可以使用该方法以非常高的产率合成范围广泛的官能化酰基环己烯产物。进行了一系列对照实验,结果表明该过程是由二醇的无受体脱氢引发的,然后是氧化还原中性级联过程,该过程与铱催化剂无关。氘标记研究表明,该级联的关键步骤涉及一种新型碱介导的 [1,5]-氢化物转移。环己烯基酮产物在弱酸性条件下很容易裂解,以获得一系列有价值的取代环己烯衍生物。