pyrromethenes

https://doi.org/10.1351/goldbook.P04965
A less preferred term for @[email protected] (The term 'pyrromethane' has been used for the system with a –CH2 linkage).
Source:
PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1361 [Terms] [Paper]