This review article discusses the literature regarding thallium(III) compounds in synthetic organic chemistry published in the last decade, including several applications in the total synthesis of natural products. The reactions that received the most attention in this period were: i) the oxidative rearrangement of chalcones; ii) the ring contraction of cyclic alkenes; iii) the oxidation of homoallylic alcohols; iv) aromatic thallations; and v) oxidative couplings, including with phenols. 1 Introduction 2 Non-Oxidative Reactions 3 Oxidative Reactions 3.1 Oxidations with Rearrangement 3.1.1 Ketones 3.1.1.1 Alkyl Aryl Ketones 3.1.1.2 Cyclic Ketones 3.1.1.3 Flavanones 3.1.1.4 Chalcones 3.1.2 Alkenes 3.1.3 Ring Opening of Cyclopropanes 3.2 Oxidations without Rearrangement 3.2.1 Cyclization Reactions 3.2.1.1 Alkenols 3.2.1.2 Carboxylic Acids 3.2.2 α-Oxidation of Ketones 3.2.3 Aromatic Thallation 3.2.4 Oxidative Coupling 3.2.4.1 Phenolic Oxidative Coupling 3.2.4.2 Non-Phenolic Oxidative Coupling 3.2.5 Oxidation of Phenols 3.2.6 Oxidation of Nitrogen Compounds 3.2.7 Disulfide Bond Formation 3.2.8 Deprotection of Thioketals 4 Miscellaneous 5 Conclusions

A metal-free protocol was developed to synthesize indanes by ring contraction of 1,2-dihydronaphthalenes promoted by PhI(OH)OTs (HTIB or Koser’s reagent). This oxidative rearrangement can be performed in several solvents (MeOH, CH3CN, 2,2,2-trifluoroethanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), and a 1:4 mixture of TFE:CH2Cl2) under mild conditions. The ring contraction diastereoselectively gives functionalized trans-1,3-disubstituted indanes, which are difficult to obtain in synthetic organic chemistry.Um protocolo livre de metais foi desenvolvido para sintetizar indanos através da contração de anel de 1,2-di-hidronaftalenos promovida por PhI(OH)OTs (HTIB ou reagente de Koser). Este rearranjo oxidativo pode ser realizado em diversos solventes (MeOH, CH3CN, 2,2,2-trifluoroetanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), e uma mistura 1:4 de TFE:CH2Cl2) em condições brandas. A contração de anel fornece indanos trans-1,3-dissubstituídos diastereosseletivamente, os quais são difíceis de obter em química orgânica sintética

An improved procedure is described for the preparation of pyranoflavylium cations from the reaction of 5,7-dihydroxy-4-methylflavylium cation with aromatic aldehydes. Modifications of the procedure of Chassaing et al. (Tetrahedron Lett. 2008, 49, 6999–7004; Tetrahedron 2015, 71, 3066–3078) circumvent the reported restriction to electron-rich benzaldehydes and provide access to a wide variety of substituted pyranoflavylium cations, including those with electron-withdrawing substituents or an attached heterocyclic or polycyclic aromatic ring. This opens the way for studies of substituent and structural effects on the ground and excited states of these pyranoanthocyanin analogues, the behavior of which should mirror fundamental aspects of the chemistry and photophysics of the pyranoanthocyanin chromophores present in mature red wines.