Oxovanadium Complex-Catalyzed Aerobic Oxidation of Propargylic Alcohols

Abstract

A catalytic system consisting of vanadium oxyacetylacetonate [VO(acac)(2)] and 3 A molecular sieves (MS3A) in acetonitrile works effectively for the aerobic oxidation of propargylic alcohols [R(1)CH(OH)Ctbd1;CR(2)] to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen. Although the reactivity of alpha-acetylenic alkanols (R(1) = alkyl) is lower compared to that of the alcohols of R(1) = aryl, alkenyl, and alkynyl, the use of VO(hfac)(2) as a catalyst and the addition of hexafluoroacetylacetone improve the product yield in these cases. A catalytic cycle involving a vanadium(V) alcoholate species and beta-hydrogen elimination from it has been proposed for this oxidation.

From Surface‐Inspired Oxovanadium Silsesquioxane Models to Active Catalysts for the Oxidation of Alcohols with O2—The Cinnamic Acid/Metavanadate System

“…The TOFs reached for the above-mentioned series of alcohols are even higher than those observed in case of the most effective oxovanadium calixarene complexes, which in turn had been superior to the reference system OVA C H T U N G T R E N N U N G (acac) 2 , reported to represent an efficient catalyst for the aerobic oxidation of 1-phenyl propargylic alcohol (see Figure 6). [15] Unfortunately, 2 is not indefinitely robust under the chosen conditions and looses nearly all activity, for instance within 40 min of catalytic oxidation of 9-hydroxyfluorene, possibly due to CO 2 elimination or C=C bond cleavage at the carboxylate ligand. It can be regenerated, though, through the addition of further equivalents of cinnamic acid, as shown in Figure 7.…”

Lewis Acid-Catalyzed Propargylic Etherification and Sulfanylation from Alcohols in MeNO2-H2O

“…This is usually achieved by converting the hydroxyl group to a metal alkoxide. [23][24][25][26] Various other useful methods employing transition metals have been reported [27][28][29][30][31][32][33][34][35][36][37][38] ; however, these methods have limited applicability. To achieve one-pot etherification, the following four processes need to be performed: i) consider the alcohol as an electrophile and activate the hydroxyl group, ii) generate a carbocation, iii) consider the alcohol as a nucleophile and form an ether, and iv) control further reactions that lead to fission of the newly formed C-O bond.…”

A Mechanistic Study on Alcohol Oxidations with Oxygen Catalysed by TPAP‐Doped Ormosils in Supercritical Carbon Dioxide

“…[2] Societal demand for fundamental chemical transformations that are not harmful to the environment is pressing, and an economically and environmentally viable replacement of current alcohol oxidation processes with heterogeneous catalytic conversions is a scientific challenge for chemists both in industry and academy. [3] Obviously, the utilization of oxygen (and even better of air) as stoichiometric oxidant for the selective oxidation of organics yielding water as sole by-product is the final, ideal goal of prolonged research efforts that in the last few years have resulted in a number of highly selective catalytic conversions based on Ru, [4] Pd, [5] Cu, [6] Co, [7] V, [8] Os [9] catalytic species.…”