使用K 12 Ga 4 L 6四面体催化剂评估主体结构对分子内Prins反应的选择性和机理的影响。通过修改螯合部分的结构和芳香族间隔基的大小来改变主体结构。虽然通常观察到螯合剂取代基的变化会影响速率的变化,但不会影响选择性,但改变主体间隔基会导致效率和产物非对映选择性的差异。观察到失误数量极高(高达 840 次)。测得的最大速率加速度约为 10 5,这是使用合成主体催化剂测得的最大过渡态稳定量级之一。据观察,宿主/客体尺寸效应在宿主介导的对映选择性中发挥重要作用。
Chiral Amide Directed Assembly of a Diastereo- and Enantiopure Supramolecular Host and its Application to Enantioselective Catalysis of Neutral Substrates
摘要:
The synthesis of a novel supramolecular tetrahedral assembly of K12Ga4L6 stoichiometry is reported. The newly designed chiral ligand exhibits high diastereoselective control during cluster formation, leading exclusively to a single diastereomer of the desired host. This new assembly also exhibits high stability toward oxidation or a low pH environment and is a more robust and efficient catalyst for asymmetric organic transformations of neutral substrates.
The effect of host structure on the selectivity and mechanism of supramolecular catalysis of Prins cyclizations
作者:William M. Hart-Cooper、Chen Zhao、Rebecca M. Triano、Parastou Yaghoubi、Haxel Lionel Ozores、Kristen N. Burford、F. Dean Toste、Robert G. Bergman、Kenneth N. Raymond
DOI:10.1039/c4sc02735c
日期:——
differences in efficiency and product diastereoselectivity. An extremelyhigh number of turnovers (up to 840) was observed. Maximum rateaccelerations were measured to be on the order of 105, which numbers among the largest magnitudes of transition state stabilization measured with a synthetic host-catalyst. Host/guest size effects were observed to play an important role in host-mediated enantioselectivity
使用K 12 Ga 4 L 6四面体催化剂评估主体结构对分子内Prins反应的选择性和机理的影响。通过修改螯合部分的结构和芳香族间隔基的大小来改变主体结构。虽然通常观察到螯合剂取代基的变化会影响速率的变化,但不会影响选择性,但改变主体间隔基会导致效率和产物非对映选择性的差异。观察到失误数量极高(高达 840 次)。测得的最大速率加速度约为 10 5,这是使用合成主体催化剂测得的最大过渡态稳定量级之一。据观察,宿主/客体尺寸效应在宿主介导的对映选择性中发挥重要作用。
Chiral Amide Directed Assembly of a Diastereo- and Enantiopure Supramolecular Host and its Application to Enantioselective Catalysis of Neutral Substrates
作者:Chen Zhao、Qing-Fu Sun、William M. Hart-Cooper、Antonio G. DiPasquale、F. Dean Toste、Robert G. Bergman、Kenneth N. Raymond
DOI:10.1021/ja411631v
日期:2013.12.18
The synthesis of a novel supramolecular tetrahedral assembly of K12Ga4L6 stoichiometry is reported. The newly designed chiral ligand exhibits high diastereoselective control during cluster formation, leading exclusively to a single diastereomer of the desired host. This new assembly also exhibits high stability toward oxidation or a low pH environment and is a more robust and efficient catalyst for asymmetric organic transformations of neutral substrates.