[{W(O)(O
<sub>2</sub>
)
<sub>2</sub>
(H
<sub>2</sub>
O)}
<sub>2</sub>
(μ‐O)]
<sup>2–</sup>
‐Catalyzed Epoxidation of Allylic Alcohols in Water with High Selectivity and Utilization of Hydrogen Peroxide
A dinuclear peroxotungstate, K2[W(O)(O2)2(H2O)}2(μ-O)]⋅2 H2O, exhibits high catalytic performance for the epoxidation of various allylic alcohols with only one equivalent of hydrogen peroxide at 305 K in water solvent. The effectiveness of this system is evidenced by high chemo-, regio-, and diastereoselectivity, and stereospecificity for the epoxidation of allylic alcohols. Furthermore, products/catalyst
A Highly Chemoselective, Diastereoselective, and Regioselective Epoxidation of Chiral Allylic Alcohols with Hydrogen Peroxide, Catalyzed by Sandwich-Type Polyoxometalates: Enhancement of Reactivity and Control of Selectivity by the Hydroxy Group through Metal−Alcoholate Bonding
作者:Waldemar Adam、Paul L. Alsters、Ronny Neumann、Chantu R. Saha-Möller、Dorit Sloboda-Rozner、Rui Zhang
DOI:10.1021/jo0266386
日期:2003.3.1
Sandwich-type polyoxometalates (POMs), namely [WZnM2(ZnW9O34)2]q- [M = Mn(II), Ru(III), Fe(III), Pd(II), Pt(II), Zn(II); q = 10-12], are shown to catalyze selectively the epoxidation of chiral allylicalcohols with 30% hydrogen peroxide under mild conditions (ca. 20 degrees C) in an aqueous/organic biphasic system. The transition metals M in the central ring of polyoxometalate do not affect the reactivity
Highly Efficient Catalytic Asymmetric Epoxidation of Allylic Alcohols by an Oxovanadium-Substituted Polyoxometalate with a Regenerative TADDOL-Derived Hydroperoxide
作者:Waldemar Adam、Paul L. Alsters、Ronny Neumann、Chantu R. Saha-Möller、Dieter Seebach、Rui Zhang
DOI:10.1021/ol027498p
日期:2003.3.1
The oxovanadium(IV) sandwich-type POM catalyzes the chemo-, regio-, and stereoselective epoxidation of allylic alcohols by chiral hydroperoxides with very high catalytic efficiency (up to 42 000 TON), a potentially valuable oxidation for the development of sustainable processes. By using the sterically demanding, TADDOL-derived hydroperoxide TADOOH as the chiral oxygen source, enantiomeric ratios (er)
Chemoselective C−H Oxidation of Alcohols to Carbonyl Compounds with Iodosobenzene Catalyzed by (Salen)chromium Complex
作者:Waldemar Adam、Feyissa Gadissa Gelalcha、Chantu R. Saha-Möller、Veit R. Stegmann
DOI:10.1021/jo9913457
日期:2000.4.1
secondary alcohols with benzylically and allylically activated C-H bonds are chemoselectively oxidized to the corresponding carbonylcompounds by the (salen)Cr(III) complex I as the catalyst and iodosobenzene as the oxygen source; the oxidizing species is the Cr(V) oxo complex. Allylicalcohols with fully substituted double bonds give appreciable amounts of epoxides besides the C-H oxidation products
Effect of Additives on Chemoselectivity and Diastereoselectivity in the Catalytic Epoxidation of Chiral Allylic Alcohols with Hydrogen Peroxide and Binuclear Manganese Complexes
作者:Hamdullah Kilic、Waldemar Adam、Paul L. Alsters
DOI:10.1021/jo801974e
日期:2009.2.6
chiral allylicalcohols 2 by manganese complexes of the cyclic triamine 1,4,7-trimethyl-1,4,7-triazacyclononane (tmtacn) 1 and hydrogen peroxide as oxygen donor in the presence of co-catalyst are investigated to understand the factors that affect the catalyst selectivity. Chemoselectivity and diastereoselectivity of catalyst 1 are significantly affected by the structure of the allylicalcohol and the
研究了在助催化剂存在下,环状三胺1,4,7-三甲基-1,4,7-三氮杂环壬烷(tmtacn)1和过氧化氢作为氧供体的锰配合物对手性烯丙基醇2的催化氧化,了解影响催化剂选择性的因素。烯丙醇的结构以及助催化剂的性质和量显着影响催化剂1的化学选择性和非对映选择性。H 2 O 2的添加摩尔当量(相对于基材为20-110 mol%)的影响更为明显。我们目前的结果反映了Mn催化剂1 / H 2的复杂氧化还原化学反应O 2 /助催化剂体系在烯烃氧化的早期阶段。