Modified cinchona alkaloid ligands: Improved selectivities in the osmium tetroxide catalyzed asymmetric dihydroxylation (AD) of terminal olefins
作者:Mark P. Arrington、Youssef L. Bennani、Thomas Göbel、Patrick Walsh、Shu-Hai Zhao、K.Barry Sharpless
DOI:10.1016/s0040-4039(00)60129-6
日期:1993.11
Modification on the quinuclidine and the quinoline moieties of the bis cinchona-alkaloid phthalazine ligands resulted in improved enantioselectivities in the osmiumtetroxidecatalyzed dihydroxylation of olefins. For the first time 1-decene, a common model for terminal aliphatic olefins, afforded enantioselectivities of over ninety percent.
A decisive step forward: A one-step fluorination on modified cinchona alkaloids produced a new range of enantiopure fluorinating agents that display high enantioselectivities in electrophilicfluorination. The first enantioselective synthesis of N-protected α-fluorophenylglycine derivatives was achieved with an enantiomeric excess up to 94 % [Eq. (a); R=Et, CN; HMDS=hexamethyldisilazanide].
向前迈出了决定性的一步:在修饰的金鸡纳生物碱上进行一步氟化,产生了一系列新的对映纯氟化剂,它们在亲电氟化中显示出高对映选择性。N-保护的α-氟苯基甘氨酸衍生物的首次对映选择性合成的对映体过量最高为94%。(一种); R = Et,CN;HMDS =六甲基二硅氮杂]。
Synthesis of Novel (9
<i>S</i>
)‐Acyloxy Derivatives of Quinidine and Dihydroquinidine as Insecticidal Agents
discover biorational natural products‐based insecticides, two series (30) of novel (9S)‐acyloxy derivatives of quinidine and dihydroquinidine were prepared and assessed for their insecticidal activity against Mythimna separata in vivo by the leaf‐dipping method at 1 mg/mL. Among all the compounds, especially four derivatives exhibited the best insecticidal activity with final mortality rates of 71.4 %
Tropolonate Salts as Acyl-Transfer Catalysts under Thermal and Photochemical Conditions: Reaction Scope and Mechanistic Insights
作者:Demelza J. M. Lyons、Claire Empel、Domenic P. Pace、An H. Dinh、Binh Khanh Mai、Rene M. Koenigs、Thanh Vinh Nguyen
DOI:10.1021/acscatal.0c03702
日期:2020.11.6
strong nucleophilicity and photochemical activity, can promote the coupling reaction between alcohols and carboxylic acid anhydrides or chlorides to give products under thermal or blue light photochemical conditions. Kinetic studies and density functional theory calculations suggest interesting mechanistic insights for reactions promoted by this acyl-transfer catalytic system.
Dual-Function Cinchona Alkaloid Catalysis: Catalytic Asymmetric Tandem Conjugate Addition−Protonation for the Direct Creation of Nonadjacent Stereocenters
作者:Yi Wang、Xiaofeng Liu、Li Deng
DOI:10.1021/ja060312n
日期:2006.3.1
addition-protonation with efficient catalytic control of two nonadjacent stereocenters. As demonstrated in a concise and highly stereoselective formal total synthesis of (-)-manzacidin A, this asymmetric tandem reaction establishes a new and versatile catalytic approach for the enantioselective and diastereoselective creation of 1,3-tertiary-quaternary stereocenters.
催化串联不对称反应构成了直接从非手性前体在非环状分子中不对称构建非相邻立体中心的有力策略。在这篇通讯中,我们报告了在双功能金鸡纳生物碱催化剂的催化下,三取代的碳供体对 2-氯丙烯腈的高度对映选择性和非对映选择性加成。这代表了第一个不对称串联共轭加成-质子化,对两个不相邻的立体中心进行有效的催化控制。正如 (-)-manzacin A 的简洁且高度立体选择性的正式全合成所证明的那样,这种不对称串联反应为 1,3-叔-四元立体中心的对映选择性和非对映选择性创建建立了一种新的通用催化方法。