1-(5-Hydroxy-2,2,8,8-tetramethyl-2H,8H-pyrano[2,3-f]chromen-6-yl)-3-(4-methoxyphenyl)prop-2-en-1-one

Abstract

In the biologically active title compound, C26H26O5, the pyran ring of the chromene unit adopts a half-chair conformation. The C=C double bond of the propenone unit exhibits a trans conformation and the carbonyl group is syn conformation to the double bond. The dihedral angle between the benzene ring and the benzopyran­one moiety is 31.54 (4)°. The mol­ecular structure is stabilized by an intra­molecular C=O⋯H—O hydrogen bond.

Synthesis and structure elucidation of a series of pyranochromene chalcones and flavanones using 1D and 2D NMR spectroscopy and X‐ray crystallography

“…Both pyranochromene rings exist in a half chair conformation with Φ = 0.3779 (11) Å, θ = 112.14 (18)°, Ψ = 219.32 (19)°and Φ = 0.3460 (11) Å, θ = 113.85 (18)° and Ψ = 146.4 (2)°, respectively. This is similar to our previous reports on similar structures …”

“…) was solved in the monoclinic space group P21/c, with one molecule in the asymmetric unit. The bond length and angles are in agreement with the expected average values for related compounds . The trans double bond is clearly evident for C‐7 and C‐8, and the 2′‐hydroxy group is on the same side of the carbonyl group with weak intramolecular hydrogen bonds being experienced by the 2′‐hydroxy and C‐9 carbonyl group.…”

“…The pyranochromene chalcones 3a–3h were synthesized according to the methods reported earlier in Pawar et al ,. and the compounds were purified by flash column chromatography to produce pure brown solids.…”