Metabolomics is an emerging and promising omics approach used to understand biological mechanisms. By untargeted and targeted metabolomics analyses, metabolites are determined in biological samples (fluids, cells, tissues, etc.) by comparison of control groups with altered groups, undergoing different therapies, submitted to differing stress levels, dietary modulation, or promoted by a disease, or specific condition, etc., using sophisticated analytical techniques, and advanced data treatment and statistical analyses. In this review, the concepts involved in metabolomics studies were presented, describing in details all steps involved in the metabolomics workflow, for untargeted and targeted strategies. Finally, the potential of metabolomics is illustrated by applications in representative areas: clinical, environmental, food and nutrition, forensic toxicology, microbiology, parasitology, plants, and sports. Relevant reviews were compiled to characterize each of these areas, and a corresponding application of untargeted and targeted metabolomics were described.

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

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