8-Azabicyclo[3.2.1]oct-3-en-2-ones via asymmetric 1,3-dipolar cycloaddition of a homochiral 3-oxidopyridinium betaine

1,3-Dipolar cycloadditions of homochiral betaine 4 proceeded in moderate to good yields, with excellent diastereofacial selectivity achieved for the major 6-exo cycloadducts 7 and 11. The absolute stereochemistry of 7 was confirmed by a single-crystal X-ray diffraction study.