Metal-catalyzed Cyclizations to Pyran and Oxazine Derivatives

NOTICE: This is the peer reviewed version of the following article: Varela, J. A., Saá, C. (2016). Metal-catalyzed Cyclizations to Pyran and Oxazine Derivatives. Synthesis, 48, 20, 3470-3478. [doi: 10.1055/s-0035-1562466]. This article may be used for non-commercial purposes in accordance with Thieme Terms and Conditions for self-archiving.Pyrans are privileged heterocyclic structures found in numerous natural compounds with extraordinary biological activities. The synthesis of these relevant structures has attracted a great deal of attention over the years. Catalytic methodologies based on the activation of neutral unsaturated functionalities of acyclic compounds that undergo intramolecular cyclizations have achieved prominent synthetic relevance. In this short review, we discuss the successful construction of dihydropyran and dihydro-1,4-oxazine derivatives from acyclic precursors by metal-catalyzed intramolecular cyclizations through carbon–carbon, carbon–oxygen, and carbon–nitrogen bond formation. Remarkable synthetic applications are highlighted.This work was supported by the Spanish MINECO (project CTQ2014-59015R), the Xunta de Galicia (project GRC2014/032) and the European Regional Development Fund (projects CTQ2014-59015R and GRC2014/032). We also thank the ORFEO-CINQA network (CTQ2014-51912REDC)S