Chemistry of α‑Oxoesters: A Powerful Tool for the Synthesis of Heterocycles Bagher Eftekhari-Sis* ,† and Maryam Zirak ‡ † Department of Chemistry, University of Maragheh, Maragheh 55181-83111, Iran ‡ Department of Chemistry, Payame Noor University, Iran * S Supporting Information CONTENTS 1. Introduction A 2. Synthesis of α-Oxoesters D 3. Synthesis of N-Heterocycles E 3.1. Aziridines and Azirines E 3.2. β-Lactams F 3.3. Pyrrolidines and Pyrrolines G 3.4. Pyrroles P 3.5. Pyrazoles R 3.6. Imidazoles V 3.7. Triazoles W 3.8. Indoles X 3.9. Pyrrolizidines and Pyrrolizines AB 3.10. Indolizidines and Indolizines AD 3.11. Imidazopyridines AH 3.12. Piperidines AI 3.13. Tetrahydro- and Dihydropyridines AJ 3.14. Pyridines AM 3.15. Fused Pyridines and Naphthyridines AO 3.16. Quinolines AS 3.17. Isoquinolines AW 3.18. β-Carbolines AX 3.19. Pyridazines AY 3.20. Pyrimidines BA 3.21. Pyrazines BB 3.22. Quinoxalines BD 3.23. Triazines BF 3.24. Azepines and Diazepines BG 3.25. Miscellaneous N-Heterocycles BI 4. Synthesis of O-Heterocycles BJ 4.1. Oxiranes BJ 4.2. Oxetanes and β-Lactones BK 4.3. Tetrahydrofurans BL 4.4. Dihydrofurans BO 4.5. Furans BW 4.6. Dioxolanes BW 4.7. Hydropyrans and Pyrans BX 4.8. Chromanes and Chromenes CI 4.9. Isochromanes and Isochromenes CM 4.10. Dioxanes CN 4.11. Oxepins CO 5. Synthesis of N,O-Heterocycles CO 5.1. Isoxazoles CO 5.2. Oxazoles CP 5.3. Oxazines CR 5.4. Oxazepines CV 6. Synthesis of N,S- and N,Se-Heterocycles CV 6.1. Thiazoles CV 6.2. Thiazines CW 6.3. Thiazepines CX 6.4. Selenazoles CX 7. Synthesis of S-, S,O-, and Si,O-Heterocycles CX 7.1. Thiophenes CX 7.2. Thiopyrans CY 7.3. Oxathiolanes CY 7.4. 1,4-Oxathianes CZ 7.5. Dioxasilocine CZ 8. Conclusion DA Associated Content DA Supporting Information DA Author Information DA Corresponding Author DA Notes DA Biographies DA Acknowledgments DB References DB 1. INTRODUCTION Heterocycles are an important class of organic compounds accounting for nearly one-third of the past decade’ s publications, which are in the field of heterocyclic chemistry. In fact, two-thirds of organic compounds are heterocyclic compounds. Heterocycles are vastly distributed in natural products, as more than 84 natural products possessing heterocyclic structural units were isolated and structurally elucidated during 2013, such as penicillactone A, B, and C, 1 gymnocin-A2, 2 oxalicumone A, B, and C, 3 illihenlactone A, B, Received: August 4, 2014 Review pubs.acs.org/CR © XXXX American Chemical Society A dx.doi.org/10.1021/cr5004216 | Chem. Rev. XXXX, XXX, XXX-XXX