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
Regio- and Diastereoselective Catalytic Epoxidation of Acyclic Allylic Alcohols with Methyltrioxorhenium: A Mechanistic Comparison with Metal (Peroxy and Peroxo Complexes) and Nonmetal (Peracids and Dioxirane) Oxidants
作者:Waldemar Adam、Catherine M. Mitchell、Chantu R. Saha-Möller
DOI:10.1021/jo9902289
日期:1999.5.1
Geraniol and its 1-methyl derivative (regiochemical probes) and a set of methyl- and tert-butyl-substituted chiral allylicalcohols (stereochemical probes) have been used to elucidate the mechanism of the MTO-catalyzed epoxidation of allylicalcohols. The regiochemical probes are preferentially epoxidized at the unfunctionalized double bond by these MTO-based oxidants, which establishes that MTO/UHP
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
Chiral Hydroperoxides as Oxygen Source in the Catalytic Stereoselective Epoxidation of Allylic Alcohols by Sandwich-Type Polyoxometalates: Control of Enantioselectivity through a Metal-Coordinated Template
作者:Waldemar Adam、Paul L. Alsters、Ronny Neumann、Chantu R. Saha-Möller、Dieter Seebach、Albert K. Beck、Rui Zhang
DOI:10.1021/jo034923z
日期:2003.10.1
The epoxidation of allylic alcohols is shown to be efficiently and selectively catalyzed by the oxidatively resistant sandwich-type polyoxometalates, POMs, namely [WZnM(2)(ZnW(9)O(34))(2)](q)(-) [M = OV(IV), Mn(II), Ru(III), Fe(III), Pd(II), Pt(II), Zn(II); q = 10-12], with organic hydroperoxides as oxygen source. Conspicuous is the fact that the nature of the transition metal M in the central ring
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。