Shortcut to a 42-Membered Trianglimine Macrocycle

Significance

The authors report the synthesis of a 42-membered trianglimine macrocycle 4. To obtain 2,2′-bipyridine-5,5′-dicarbaldehyde 3, the key compound in their synthetic pathway, the dimethyl-bipyridine 1 was first transformed to 2 using Bredereck’s reagent. Subsequent oxidative cleavage led to the formation of 3 in 72% yield. The following [3+3] cyclocondensation afforded 4 as the only product in 84% yield after 24 hours at room temperature.