A selectivity study of activated ketal reduction with borane dimethyl sulfide
摘要:
A chemo- and regioselectivity study of the reagent combination BH3.SMe2/TMSOTf for ketal reduction has been undertaken. It has revealed that simple 1,3-dioxanes reduce cleanly at low temperature in CH2Cl2 while simple 1,3-dioxolanes may give complete ring cleavage and dimerization products. A study of reduction of 4-substituted 1,3-dioxolanes has revealed a solvent-directed regioselectivity which in THF favors the secondary protected derivative. A mechanism is postulated to account for the selectivities based on recent thinking on acetal substitution reactions.
Iron(II) Complexes with Bio-Inspired N,N,O Ligands as Oxidation Catalysts: Olefin Epoxidation andcis-Dihydroxylation
作者:Pieter C. A. Bruijnincx、Inge L. C. Buurmans、Silvia Gosiewska、Marcel A. H. Moelands、Martin Lutz、Anthony L. Spek、Gerard van Koten、Robertus J. M. Klein Gebbink
DOI:10.1002/chem.200700573
日期:2008.1.28
iron(II) coordination chemistry of the ligands 3,3-bis(1-methylimidazol-2-yl)propionate (L1) and its neutral propyl ester analogue propyl 3,3-bis(1-methylimidazol-2-yl)propionate (PrL1). The molecular structures of two iron(II) complexes with PrL1 were determined and two different coordination modes of the ligand were observed. In [Fe(II)(PrL1)(2)](BPh(4))(2) (3) the ligand is facially coordinated to the metal
Iron-Catalyzed Olefin Epoxidation in the Presence of Acetic Acid: Insights into the Nature of the Metal-Based Oxidant
作者:Rubén Mas-Ballesté、Lawrence Que
DOI:10.1021/ja075115i
日期:2007.12.1
[BPMEN = N,N'-bis-(2-pyridylmethyl)-N,N'-dimethyl-1,2-ethylenediamine; TPA = tris-(2-pyridylmethyl)amine] catalyze the oxidation of olefins by H2O2 to yield epoxides and cis-diols. The addition of acetic acid inhibits olefin cis-dihydroxylation and enhances epoxidation for both 1 and 2. Reactions carried out at 0 degrees C with 0.5 mol % catalyst and a 1:1.5 olefin/H2O2 ratio in a 1:2 CH3CN/CH3COOH
Regio- and Stereoselective Reduction of Diketones and Oxidation of Diols by Biocatalytic Hydrogen Transfer
作者:Klaus Edegger、Wolfgang Stampfer、Birgit Seisser、Kurt Faber、Sandra F. Mayer、Reinhold Oehrlein、Andreas Hafner、Wolfgang Kroutil
DOI:10.1002/ejoc.200500839
日期:2006.4
The asymmetric reduction of symmetrical and nonsymmetrical diketones as well as the stereoselectiveoxidation of various diols by biocatalytic hydrogen transfer was investigated by employing lyophilized cells of Rhodococcus ruber DSM 44541 containing alcohol dehydrogense ADH-‘A’. Symmetrical and nonsymmetrical diketones at the (ω-1)- and (ω-2)-positions are reduced to the Prelog product with high stereopreference
High conversion of olefins to cis-diols by non-heme iron catalysts and H2O2
作者:Ju Yeon Ryu、Jinheung Kim、Miquel Costas、Kui Chen、Wonwoo Nam、Lawrence Que Jr.
DOI:10.1039/b203154j
日期:2002.5.30
Efficient and highly stereoselective oxidation of olefins to cis-diols as the major product is obtained by using biomimetic non-heme FeII catalysts in combination with H2O2.
Olefin-Dependent Discrimination between Two Nonheme HOFe<sup>V</sup>O Tautomeric Species in Catalytic H<sub>2</sub>O<sub>2</sub>Epoxidations
作者:Anna Company、Yan Feng、Mireia Güell、Xavi Ribas、Josep M. Luis、Lawrence Que、Miquel Costas
DOI:10.1002/chem.200802597
日期:2009.3.23
water incorporation into products (up to 75 %) is observed in epoxidation reactions with H2O2 by a bioinspired nonheme iron catalyst. A surprising substrate‐dependent incorporation of water is observed, and is proposed to arise from fast equilibrium betweentwo high‐valent HOFeVO isomeric species exhibiting different reactivity.
湿式加氧酶模型:在通过生物启发的非血红素铁催化剂与H 2 O 2进行的环氧化反应中,观察到前所未有的高水平的水混入产品(高达75%)。水的令人惊讶的衬底依赖性掺入观察到的,并提出了两个高价HO之间从快速平衡出现铁V表现出不同的反应性O异构体物种。