Highly Enantioselective Catalytic Kinetic Resolution of α‐Branched Aldehydes through Formal Cycloaddition with Homophthalic Anhydrides
作者:Umar Farid、Maria Luisa Aiello、Stephen J. Connon
DOI:10.1002/chem.201902422
日期:2019.8
A new catalytic methodology was developed to promote an efficient one‐pot kinetic resolution of racemic aldehydes with selectivity (s*) of up to 91 (99:1 d.r., >99 % ee) in a cycloaddition reaction with enolizable anhydrides to afford dihydroisocoumarin products (a core prevalent in natural products and molecules of medicinal interest) containing three contiguous stereocentres.
Boron Trifluoride Etherate-Controlled Reactions of Methyl Enol Ethers: Selective Synthesis of Dihydrofuro[3,2-c]chromenone and Furo[3,2-c]chromenone Derivatives
作者:Faiz Ahmed Khan、Sarwat Asma Ziya Ahmad
DOI:10.1055/a-1912-3884
日期:——
A facile one-step synthetic approach to dihydrofuro-[3,2-c]chromenones and furo[3,2-c]chromenones by the reaction of methyl enol ethers with 4-hydroxycoumarins under metal-free conditions is presented. Dihydrofuro[3,2-c]chromenones and furo[3,2-c]-chromenones were selectively obtained by controlling the stoichiometry of boron trifluoride diethyl etherate. An unexpected aryl-group migration followed
提出了一种在无金属条件下通过甲基烯醇醚与 4-羟基香豆素反应来简便地一步合成二氢呋喃-[3,2- c ]色酮和呋喃[3,2 - c ]色酮的方法。通过控制三氟化硼乙醚合物的化学计量,选择性地得到二氢呋喃[3,2- c ]色酮和呋喃[3,2- c ]-色酮。据报道,芳基迁移后呋喃部分芳构化,导致各种呋喃[3,2- c ]色烯酮衍生物的收率良好。
A Simple Primary Amine Catalyst for Enantioselective α-Hydroxylations and α-Fluorinations of Branched Aldehydes
作者:Michael R. Witten、Eric N. Jacobsen
DOI:10.1021/acs.orglett.5b01193
日期:2015.6.5
A new primary amine catalyst for the asymmetric a-hydroxylation and a-fluorination of alpha-branched aldehydes is described. The products of the title transformations are generated in excellent yields with high enantioselectivities. Both processes can be performed within short reaction times and on gram scale. The similarity in results obtained in both reactions, combined with computational evidence, implies a common basis for stereoinduction and the possibility of a general catalytic mechanism for a-functionalizations. Promising initial results in alpha-amination and alpha-chlorination reactions support this hypothesis.