Oxidative functional group transformations with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
作者:Noritaka Mizuno、Keigo Kamata、Kazuya Yamaguchi
DOI:10.1016/j.cattod.2011.07.007
日期:2012.5
equivalent H+ to form a bis-μ-hydroxo species [γ-PW10O38V2(μ-OH)2]3− (I′) in organic media. The strong electrophilic oxidants such as [γ-PW10O38V2(μ-OH)(μ-OOH)]3− (II) and [γ-PW10O38V2(μ-η2:η2-O2)]3− (III) are formed by the reaction of the bis-μ-hydroxo species with H2O2. In the presence of I and H+, H2O2-based oxidations such as (i) epoxidation of alkenes (17 examples including electron-deficient ones),
甲二钒取代的磷钨TBA 4 [γ-PW 10 ö 38 V 2(μ-OH)(μ-O)](我,TBA =四Ñ -butylammonium)与一种当量H起反应+以形成双- μ -hydroxo物种[γ-PW 10 ö 38 V 2(μ-OH)2 ] 3-(我')在有机介质中。强电氧化剂如[γ-PW 10 ö 38 V 2(μ-OH)(μ-OOH)] 3-(II)和[γ-PW 10 ö 38 V 2(μ-η 2:η 2 -O 2)] 3-(III)是通过用H双- μ-羟物种的反应形成2 Ò 2。在I和H +的存在下,基于H 2 O 2的氧化,例如(i)烯烃的环氧化(17个实例,包括缺电子的烯烃),(ii)烷烃的羟基化(11个实例),以及(iii)氧化烯烃,炔烃,并与溴芳烃的溴化-作为溴源(包括氯化的12个例子),化学,非对映体和区域选择性地以中等至高收率,高效率地利用H 2 O 2来产生相应的氧化产物。
Carbon Dioxide as a Protecting Group: Highly Efficient and Selective Catalytic Access to Cyclic<i>cis</i>-Diol Scaffolds
作者:Victor Laserna、Giulia Fiorani、Christopher J. Whiteoak、Eddy Martin、Eduardo Escudero-Adán、Arjan W. Kleij
DOI:10.1002/anie.201406645
日期:2014.9.22
The efficient and highly selective formation of a wide range of (hetero)cyclic cis‐diol scaffolds using aminotriphenolate‐based metal catalysts is reported. The key intermediates are cyclic carbonates, which are obtained in high yield and with high levels of diastereo‐ and chemoselectivity from the parent oxirane precursors and carbon dioxide. Deprotection of the carbonate structures affords synthetically