Potentiality and Synthesis of O- and N-Heterocycles: Pd-Catalyzed Cyclocarbonylative Sonogashira Coupling as a Valuable Route to Phthalans, Isochromans, and Isoindolines

Oxygen and nitrogen heterocycle systems are found in a vast number of natural substrates and biologically active molecules. In particular, phthalan, isochroman, and isoindoline scaffolds are present in many classes of products such as anti-mycotics, antibiotics, antioxidants, pigments, and fluorophores. Therefore several procedure dedicated to the building of such heterocycles have been developed. In this review a detailed analysis of literature data relating to these scaffolds is described. Particular attention has been devoted to their biological and chemical potentiality, and an in-depth investigation into the most important synthetic methods is reported. Cyclo-carbonylative Sonogashira coupling of suitable alcohols and amides has been carefully considered, because it represents a valuable and atom-economic route for the construction of alkylidenephthalans, -isochromans, and -isoindolines.