“…Moreover, the 13 C‐NMR spectrum of 5a showed signals at δ 185.84 (C═O, pyridinone), 158.63 (C═O, lactone), and 154.50 (C═P). In the 31 P‐NMR spectrum of compound 5a , a signal was observed at δ = 28.07, which is in agreement with a phosphorane on a six‐membered ring system . The third product was 3‐(phenylimino)‐3 H ,5 H ‐chromeno[3′,4′:4,5]pyrrolo[1,2‐ c ][1,2,3]triazol‐5‐one ( 8 ).…”