Selective 6π‐Electrocyclization of <i>N</i>‐Vinyl‐<i>α</i>,<i>β</i>‐Unsaturated Nitrones to Prepare Polysubstituted Pyridine Derivatives

Comprehensive Summary Herein, we have developed a facile method for the synthesis of various polysubstituted pyridine derivatives through selective 6π‐electrocyclization of N ‐vinyl‐ α , β ‐unsaturated nitrones. It was found that gold catalysts promoted carbon‐6π‐electrocyclization of N ‐vinyl‐ α , β ‐unsaturated nitrones to afford 6‐alkenyl pyridine N ‐oxides in 43%—75% yields, whereas copper catalysts facilitated oxygen‐6π‐electrocyclization to give 6‐epoxy pyridines in 41%—83% yields. The present method features broad substrate scope, good functional group tolerance, high cyclization selectivity, and diversity of polysubstituted pyridine scaffolds.