Chemo- and stereoselectivity in the ring-openingreaction of epoxides with a reagent prepared from allylmagnesium halide and chlorotitanium triphenoxide is described. It has been proven that the allylating reagent can also be used for the reaction of epoxides bearing a tert-butyl ester, amide, or acetal moiety, and that the epoxide cleavage regioselectively takes place at the more substituted carbon
Iron Catalyzed Highly Enantioselective Epoxidation of Cyclic Aliphatic Enones with Aqueous H<sub>2</sub>O<sub>2</sub>
作者:Olaf Cussó、Marco Cianfanelli、Xavi Ribas、Robertus J. M. Klein Gebbink、Miquel Costas
DOI:10.1021/jacs.5b12681
日期:2016.3.2
An iron complex with a C1-symmetric tetradentate N-based ligand catalyzes the asymmetric epoxidation of cyclic enones and cyclohexene ketones with aqueous hydrogen peroxide, providing the corresponding epoxides in good to excellent yields and enantioselectivities (up to 99% yield, and 95% ee), under mild conditions and in short reaction times. Evidence is provided that reactions involve an electrophilic
具有 C1 对称四齿 N 基配体的铁配合物催化环烯酮和环己烯酮与过氧化氢水溶液的不对称环氧化反应,提供相应的环氧化物,产率和对映选择性都很好(高达 99% 和 95% ee ),条件温和,反应时间短。有证据表明反应涉及亲电氧化剂,并且该元素用于对包含两个烯烃位点的烯酮进行位点选择性环氧化。
METHOD FOR PRODUCING CHIRAL ALPHA,BETA-EPOXY KETONES
申请人:List Benjamin
公开号:US20110009650A1
公开(公告)日:2011-01-13
A process is claimed for the enantioselective epoxidation of α,β-unsaturated ketones, in which a compound of the general formula I,
is reacted with an oxidizing agent to form α,β-epoxy ketones of the general formula II,
in which R
1
, R
2
, R
3
are as defined above. The α,β-epoxy ketones of the general formula II can be obtained in good yields and outstanding enantioselectivities from α,β-unsaturated ketones of the general formula I by epoxidation with hydrogen peroxide in the presence of a chiral catalyst, such as amino compounds and their acid addition salts.
Highly enantioselective epoxidation of olefins by H<sub>2</sub>O<sub>2</sub> catalyzed by a non-heme Fe(<scp>ii</scp>) catalyst of a chiral tetradentate ligand
作者:Mainak Mitra、Olaf Cusso、Satish S. Bhat、Mingzhe Sun、Marco Cianfanelli、Miquel Costas、Ebbe Nordlander
DOI:10.1039/c8dt04449j
日期:——
ability of the iron complex to catalyze asymmetric epoxidation reactions of olefins with H2O2 was investigated, using 2-cyclohexen-1-one, 2-cyclopenten-1-one, cis-β-methylstyrene, isophorone, chalcones and tetralones as substrates. Different carboxylic acids were used as additives to enhance yields and enantioselectivities, and 2-ethylhexanoic acid was found to give the best results. The catalysis results
手性四齿N4-供体配体1-甲基-2-((S)-2-[(S)-1-(1-甲基苯并咪唑-2-基甲基)吡咯烷-2-基]吡咯烷-1-基}基于手性二吡咯烷骨架的}甲基)苯并咪唑(S,S - PDBz L)已合成,并已制备并表征了其相应的Fe(II)配合物。配合物的X射线结构表明,Fe(II)离子处于扭曲的八面体配位环境中,两个顺式取向配位点被(不稳定的)三氟甲磺酸根阴离子占据。铁络合物催化烯烃与H 2 O 2的不对称环氧化反应的能力以2-环己烯-1-酮,2-环戊烯-1-酮,顺式-β-甲基苯乙烯,异佛尔酮,查耳酮和四氢萘酮为底物进行了研究。使用不同的羧酸作为添加剂来提高收率和对映选择性,发现2-乙基己酸的效果最佳。催化结果表明,Fe(II)配合物能够在环氧化反应中实现相对较高的对映选择性(> 80%)。