已在碱性溶液中确定了将硼氢化钠加至3取代的5,5-二甲基环己-2-烯酮(1),对位取代的3-苯基环己烯酮(2)和对位取代的苯乙酮(3)的速率常数。(NaOH,0.025 mol l –1)的水-二恶烷(1:1 v / v)在298 K下。在这些条件下,共轭环己烯酮体系(1)和(2)进行排他的1,2-还原,生成相应的烯丙醇。讨论了还原的区域选择性。速率常数与σp或σp +之间获得的线性自由能关系证实这些3-取代的环己烯酮结构是研究取代基对烯键体系反应性影响的良好模型。对这三个系列的反应常数进行比较得出的结论是,就苯乙酮的硼氢化物还原而言,环己烯酮还原必须在反应坐标的最后四分之一处具有较晚的过渡态。
Transmission of substituent effects through unsaturated systems. Part 6. Kinetics of reduction of β-substituted α,β-unsaturated ketones with sodium borohydride
regioselectivity of reduction is discussed. The linear free energy relationships obtained between the rate constants and σp or σp+ confirm that these 3-substituted cyclohexenone structures are good models for the investigation of the substituent effects on the reactivity of ethylenic systems. Comparison of reaction constants for the three series leads to the conclusion that, as for borohydridereductions of acetophenone
已在碱性溶液中确定了将硼氢化钠加至3取代的5,5-二甲基环己-2-烯酮(1),对位取代的3-苯基环己烯酮(2)和对位取代的苯乙酮(3)的速率常数。(NaOH,0.025 mol l –1)的水-二恶烷(1:1 v / v)在298 K下。在这些条件下,共轭环己烯酮体系(1)和(2)进行排他的1,2-还原,生成相应的烯丙醇。讨论了还原的区域选择性。速率常数与σp或σp +之间获得的线性自由能关系证实这些3-取代的环己烯酮结构是研究取代基对烯键体系反应性影响的良好模型。对这三个系列的反应常数进行比较得出的结论是,就苯乙酮的硼氢化物还原而言,环己烯酮还原必须在反应坐标的最后四分之一处具有较晚的过渡态。
Total synthesis of (+)-<i>ar</i>-macrocarpene
作者:Arindam Khatua、Sovan Niyogi、Vishnumaya Bisai
DOI:10.1039/c9ob01373c
日期:——
catalytic asymmetric total synthesis of a sesquiterpene, (+)-ar-macrocarpene (1), in 7 steps with 42.1% overall yields from commercially available inexpensive 5,5-dimethylcyclohexane 1,3-dione. This strategy relies on a key [3,3]-sigmatropic rearrangement effecting reductive transposition through allylic diazene rearrangement (ADR) in a single step from intermediate allylic alcohol (+)-12 under the Mitsunobu
A palladium-catalyzed synthesis of cyclic alkenyl boronates from alkenyl chlorides
作者:Hongru Ou、Xu Zhao、Yunfei Luo
DOI:10.1039/d3ob01931d
日期:——
A palladium-catalyzed borylation of cyclic alkenyl chlorides with B2pin2 is reported. This transformation allows for the conversion of diverse cyclic alkenyl chlorides into synthetically versatile alkenyl boronates with moderate to excellent yields. The utility of this reaction has been demonstrated with practical Suzuki–Miyaura coupling and aziridination reactions, which allow access to functionalized
报道了钯催化的环烯基氯与 B 2 pin 2的硼基化反应。这种转化允许将不同的环状烯基氯转化为合成通用的烯基硼酸酯,并具有中等至优异的产率。该反应的实用性已通过实际的铃木-宫浦偶联和氮丙啶化反应得到证明,这些反应可以得到官能化烯烃和有价值的硼取代氮丙啶。