title: Absolute Configuration Determination by Quantum Mechanical Calculation of Chiroptical Spectra: Basics and Applications to Fungal Metabolites.
abstract: BACKGROUND
  Quantum mechanical simulations of chiroptical properties, such as electronic circular dichroism (ECD), optical rotation (OR), and vibrational circular dichroism (VCD), have rapidly become very popular to assign the absolute configuration of novel natural products.
  
  
  OBJECTIVE
  We review the application of the ECD/OR/VCD computational methodology to chiral metabolites of fungal origin. First, we summarize the fundamentals of the three spectroscopies; then, we focus on the specific experimental and computational issues allied to the application of their calculations.
  
  
  METHODS
  We surveyed the entire literature describing the use of ECD/OR/VCD computations for fungal metabolites, and catalogued all papers according to the method employed and to the structural family of compounds. Then, we chose several examples to illustrate the use of the techniques and highlight the practical application of the computational approach.
  
  
  RESULTS
  Our literature survey demonstrates that the simulation of ECD/OR/VCD spectra is nowadays widespread and accessible also to non-experts, although a good computational practice is necessary to avoid wrong assignments. ECD is still the most common technique used in the context of fungal metabolites. OR and VCD may be profitably employed when the compound of interest lacks chromophoric groups. Our examples illustrate that the combination of two or more chiroptical methods is strongly advisable in some cases, especially in the presence of high conformational flexibility, where a single technique does not lead to a safe conclusion.
  
  
  CONCLUSIONS
  The ECD/OR/VCD computational approach is a reliable and versatile method to assign the absolute configuration of fungal metabolites and related natural products.
authors.affiliation: Dipartimento di Scienze, Universita della Basilicata, Potenza, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Superchi
authors.affiliation: Dipartimento di Scienze, Universita della Basilicata, Potenza, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Scafato
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Universita di Pisa, Pisa, Italy.
authors.forename: Marcin
authors.initials: M
authors.lastname: Gorecki
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Universita di Pisa, Pisa, Italy.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Pescitelli
mesh_terms: D002942:Circular Dichroism; D005658:Fungi / Q000378:metabolism*; D055620:Optical Phenomena; D011789:Quantum Theory
keywords: Structure elucidation; conformational analysis; density functional theory; electronic circular dichroism; natural products; optical rotation; vibrational
  circular dichroism