Naturally occurring substances containing a
cis-fused tetrahydrochromeno[3,4-
b]chromene nucleus. Many rotenoids contain an additional ring, e.g rotenone:
R05417.png
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1364 (https://doi.org/10.1351/pac199567081307)