Cyclization and Cycloisomerization of π-Tethered Ynamides: An Expedient Synthetic Method to Construct Carbo- and Heterocycles

Stable ynamides are used for the development of novel synthetic transformations and the construction of unusual carbo/heterocycles. The intramolecular cyclization of -tethered alkene/alkyne/allene-ynamides is studied extensively for the fabrication of a wide range of molecular scaffolds for various applications. The ketene-acetal/aminal generated in situ from -tethered ynamides participates in intramolecular cyclization/cycloisomerization processes to yield N-bearing fused heterocycles. This account summarizes the scientific merits and the advances made in cyclization and cycloisomerization strategies for stable -tethered alkene/alkyne/allene-ynamides. 1 Introduction 2-Tethered Ynamides 3 Alkene-Tethered Ynamides 4 Alkyne-Tethered Ynamides 5 Allene-Tethered Ynamides 6 Concluding Remarks