Many substances of forensic interest are chiral and available either as racemates or pure enantiomers. Application of chiral analysis in biological samples can be useful for the determination of legal or illicit drugs consumption or interpretation of unexpected toxicological effects. Chiral substances can also be found in environmental samples and revealed to be useful for determination of community drug usage (sewage epidemiology), identification of illicit drug manufacturing locations, illegal discharge of sewage and in environmental risk assessment. Thus, the purpose of this paper is to provide an overview of the application of chiral analysis in biological and environmental samples and their relevance in the forensic field. Most frequently analytical methods used to quantify the enantiomers are liquid and gas chromatography using both indirect, with enantiomerically pure derivatizing reagents, and direct methods recurring to chiral stationary phases.

Xanthones belong to a class of O-heterocycles which are known for their great variety of biological/pharmacological activities. The xanthone scaffold can be considered as a privileged structure and for that reason it is an excellent starting point for the search of new bioactive molecules. This review intends not only to make a literature survey about the synthesis of xanthones, but also to organize the most important and common syntheses that have been published from 2005 to 2012 in an integrative way. Among the new developed approaches, we highlight the synthesis of xanthones via benzyne, palladium-catalyzed, domino type reactions and imidazolidenyl carbene-catalyzed reactions. In the first three sections it is given an overview about the classic synthetic approaches, focusing on recent developments; the fourth section orders different approaches described for the synthesis of xanthones using chromen-4-ones as building blocks. As far as our knowledge, this is the first time that a review systematizes the synthesis of xanthones based on chromen-4-ones. The fifth section refers to a miscellaneous of synthetic approaches that do not fit in any of the previous but nevertheless are useful. The last section is devoted to molecular modifications that can be done directly from the xanthone scaffold.