Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• ][78][95] less reactive and less electron-deficient N-oxyl radicals (usually isolable and storable amine-N-oxyl radicals) are used as precursors of the active oxidants, oxoammonium cations. This oxidative organocatalysis type is highly important for the chemoselective oxidation of alcohols. Two

Synthesis of acremines A, B and F and studies on the bisacremines

• Nils Winter and
• Dirk Trauner

Beilstein J. Org. Chem. 2019, 15, 2271–2276, doi:10.3762/bjoc.15.219

• isolated from fungi of the genus Acremonium. Here, we present the asymmetric total synthesis of acremine F which hinges on a modestly enantioselective dihydroxylation and a subsequent kinetic resolution via a highly selective asymmetric reduction. Chemoselective oxidation of acremine F gave access to

Base metal-catalyzed benzylic oxidation of (aryl)(heteroaryl)methanes with molecular oxygen

• Hans Sterckx,
• Johan De Houwer,
• Carl Mensch,
• Wouter Herrebout,
• Kourosch Abbaspour Tehrani and
• Bert U. W. Maes

Beilstein J. Org. Chem. 2016, 12, 144–153, doi:10.3762/bjoc.12.16

• metabolites is therefore of great importance to facilitate the drug discovery process [42]. For this purpose chemoselective oxidation protocols are a valuable tool since they can provide us with metabolites typically generated by cytochrome P450 enzymes. Bearing this in mind we attempted to oxygenate the

• features two oxidation sensitive veratrole units. Interestingly, a highly chemoselective oxidation was observed and compound 15 was isolated in 60% yield. Trace metal analysis When using transition metal catalysis in the synthesis of compounds designated for application (pharmaceuticals, agrochemicals

• high temperatures the authors switched to propylene carbonate as the solvent. Chemoselectivity When multiple activated methylene motifs are present the chemoselective oxidation of one of these positions can be achieved as we previously exemplified for 2-methyl-6-(4-methylbenzyl)pyridine (18b, Table 5

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• tetrahydropyran 92 as key intermediate of the synthesis. Oxidation of 92 and heating to 220 ºC resulted in a concurrent selenoxide elimination and Claisen rearrangement to give 93 via intermediate 81. Face-selective Simmons–Smith cyclopropanation, reduction of both carbonyl groups, and chemoselective oxidation of

A protecting group-free synthesis of the Colorado potato beetle pheromone

• Zhongtao Wu,
• Manuel Jäger,
• Jeffrey Buter and
• Adriaan J. Minnaard

Beilstein J. Org. Chem. 2013, 9, 2374–2377, doi:10.3762/bjoc.9.273

• ) in the presence of either benzoquinone or air as the terminal oxidant [12]. More recently, the transformation of unprotected vicinal polyols to α-hydroxy ketones was achieved by regio- and chemoselective oxidation using catalyst 2 [13]. We used this method for the catalytic regioselective oxidation

• of glycosides (Scheme 1) [14] and expected that the approach might also be applicable in the synthesis of (S)-1. Triol 3, with vicinal primary, secondary, and tertiary hydroxy groups should be a suitable substrate for chemoselective oxidation with catalyst 2, enabling a protecting group-free

NHC-catalysed highly selective aerobic oxidation of nonactivated aldehydes

• Lennart Möhlmann,
• Stefan Ludwig and
• Siegfried Blechert

Beilstein J. Org. Chem. 2013, 9, 602–607, doi:10.3762/bjoc.9.65

• of aldehydes to the corresponding acids or esters. The reaction proceeds under metal-free conditions by using N-heterocyclic carbenes as organocatalysts in combination with environmentally friendly oxygen as the terminal oxidation agent. Keywords: aerobic oxidation; chemoselective oxidation; metal