Isoflavans are compounds with a 3-phenyl-3,4-dihydro-2\(H\)-1-benzopyran skeleton (see isoflavonoids). They may be substituted.
Source:
PAC, 2018, 90, 1429. 'Nomenclature of flavonoids (IUPAC Recommendations 2017)' on page 1433 (https://doi.org/10.1515/pac-2013-0919)