Asymmetric Hetero Diels-Alder Reactions

Abstract

Asymmetric hetero Diels-Alder reactions provide a multitude of opportunities for the highly efficient regio- and stereoselective construction of various heterocycles in enantiomerically pure form. Despite the great potential of this synthetic methodology, its development was for a long time restricted to only a few efforts. However, during the last decade this field has been the subject of intense and successful activities. This review summarizes the progress which has been made in the development of efficient chiral auxiliary groups and catalysts for the steric steering of aza, oxa and thia Diels-Alder cycloadditions and thereby describes the current state of the art. 1. Introduction 2. Aza Diels-Alder Reactions 2.1. Imino Dienophiles and Dienes 2.1.1. C- and N-Acylimines and N-Acylazo Compounds as Dienophiles and Dienes 2.1.2. Imines and Iminium Salts as Dienophiles and Dienes 2.2. N-Sulfinyl Dienophiles 2.3. Nitroso and Nitro Dienophiles and Dienes 2.3.1. Nitroso Compounds as Dienophiles 2.3.2. Nitroso Compounds as Dienes 2.3.3. Nitro Compounds as Dienes 3. Oxa Diels-Alder Reactions 3.1. Carbonyl Dienophiles 3.2. Oxabutadienes 4. Thia Diels-Alder Reactions 5. Miscellaneous 6. Conclusion