Lithium promoted mesoporous manganese oxide catalyzed oxidation of allyl ethers

Abstract

Herein we report the first example of the catalytic aerobic partial oxidation of allyl ether to its acrylate ester derivative. Many partial oxidations often need an expensive oxidant such as peroxides or other species to drive such reactions. In addition, selective generation of esters using porous catalysts has been elusive. This reaction is catalyzed by a Li ion promoted mesoporous manganese oxide (meso-Mn2O3) under mild conditions with no precious metals, a reusable heterogeneous catalyst, and easy isolation. This process is very attractive for the oxidation of allyl ethers. We report on the catalytic activity, selectivity, and scope of the reaction. In the best cases presented, almost complete conversion of allyl ether with near complete chemo-selectivity towards acrylate ester derivatives is observed. Based on results from controlled experiments, we propose a possible reaction mechanism for the case in which N-hydroxyphthalimide (NHPI) is used in combination with trichloroacetonitrile (CCl3CN).

Aerobic and Additive‐free Oxidative Dehydrogenation of N‐heterocycles over Commercial MnCO3‐derived Manganese Oxides

“…Inspired by manganese-oxide catalysts with high activity towards oxidation reactions [19][20][21][22] , and encouraged by our recent investigations on preparing heterogeneous manganese catalysts for alcohol oxidation reactions [23,24] . Herein, we use commercial MnCO 3 as the precursor to prepare manganese oxides by simply pyrolyzing it at 400°C under an air atmosphere.…”

Asymmetric Allylic C–H Alkylation of Allyl Ethers with 2-Acylimidazoles

“…Previous endeavors toward the palladium-catalyzed allylic C–H functionalization have allowed the tolerance of a wide range of terminal alkenes, even in asymmetric variants. , However, the allylic C–H alkylation of allyl ethers, which holds the potential to provide an additional and modifiable functional group, has been rarely investigated. A major challenge to access this transformation presumably arises from the fact that allyl ethers can undergo C–O cleavage with a palladium catalyst to generate π-allyl palladium intermediates for Tsuji–Trost type allylic substitution (Scheme b) .…”

Technological Aspects of Highly Selective Synthesis of Allyloxyalcohols—New, Greener, Productive Methods

“…Recently, the importance of the thiol-ene "click chemistry" with allyl ethers in the environmentally friendly polymer coatings, material science, dendrimers, surface modification, and biotechnology areas, is constantly increasing [18]. Additionally, big progress has been achieved in the field of the green oxidation processes of the double bond of allyl functionality, especially in the direct epoxidation towards glycidyl ethers or aerobic catalytic oxidation to acrylates [19,20] with using the safe, easy to handle and cheap oxidants such as hydrogen peroxide (H 2 O 2 ) or oxygen (O 2 ) and without generating toxic by-products. The attractive pathway for the synthesis of fine and specialty chemicals such as alkyl glycerol monoethers (GMEs) is the well-known direct dihydroxylation of alkyl allyl ethers under oxidative conditions [21][22][23], including the high stereoselective synthesis of dihydroxyether derivatives [24].…”

“…On the other hand, the presence of hydroxyl group in the allyloxyalcohol molecule opens the way for easily synthetic pathways of the valuable allyl ether functionalized monomers/oligomers/polymers with a large variety of different reactive groups (Scheme 1, right side). First, the well-known simple esterification (condensation or polycondensation) reaction of various organic dicarboxylic acids/anhydrides typically phthalic, maleic, isophthalic, terephthalic, adipic, or succinic ones and fatty acids, creates the possibility of producing polymerizable multifunctional allyl ether carboxylate ester monomer hybrid systems, including hyperbranched polymers or unsaturated polyester resins (UPRs) [19][20][21][22][23][24][25]. The introduction of an allyloxy alkyl group from allyloxyalcohol instead of a simple allyl group from allyl alcohol gives the monomer molecules provides regulated length of their carbon chain, and, in consequence, changes the properties of resulted polymeric materials.…”