Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.004 Å; R factor = 0.059; wR factor = 0.180; data-to-parameter ratio = 17.6.In the racemic title compound, C 21 H 18 O 4 , the chromone ring is essentially planar [maximum deviation from the least-squares plane = 0.026 (3) Å ], with a dihedral angle of 78.18 (12) between the benzene rings of the chromanone and chromenone moieties. In the crystal, there are weak -stacking interactions [minimum ring centroid separation = 3.9286 (17) Å ].
Related literature
Halogen‐exchange (Halex) fluorinations in vinylic systems are rare; under controlled conditions, halex fluorination of vinylic aldehydes, 1‐chloro‐3H‐benzo[f]chromene‐2‐carbaldehyde (8) and 4‐chloro‐2H‐benzo[h]chromene‐3‐carbaldehyde (11) successfully furnished their respective fluoro exchanged derivatives 1‐fluoro‐3H‐benzo[f]chromene‐2‐carbaldehyde 9 and 4‐fluoro‐2H‐benzo[h]chromene‐3‐carbaldehyde 12. However, 4‐chlorobenzopyran‐3‐carbadehydes (3) underwent a novel cascade reaction exclusively via the fluorine exchanged intermediate to afford 2,3‐dihydro‐3,3′‐methylenebischromones (4). Under similar conditions, in a somewhat different manner, the thio analogous system, 4‐chlorobenzothiopyran‐3‐carbaldehydes (1) yielded 3,3′‐methylene bisthiochromen‐4‐ones (2) also in a domino fashion. Sterically hindered vinylic aldehyde, 4‐chloro‐2,2‐dimethyl‐benzopyran‐3‐carbaldehyde (18) exhibited a totally different behavior by affording a bicyclic benzopyran annulated bisacetal (19). The mechanism of these transformations has been investigated.
4,4′-bichromenes and 4,4′-bithiochromenes have been synthesized by a Ni catalyzed homocoupling method and their Atropisomeric behavior has been studied.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.