Crystal structure of a photobiologically active brominated angular pyran-ocoumarin: bromo-hy-droxy-seselin

A K Bauri; Sabine Foro; A F M Mustafizur Rahman

doi:10.1107/S2056989017002808

Crystal structure of a photobiologically active brominated angular pyran-ocoumarin: bromo-hy-droxy-seselin

Acta Crystallogr E Crystallogr Commun. 2017 Feb 28;73(Pt 3):453-455. doi: 10.1107/S2056989017002808. eCollection 2017 Mar 1.

Authors

A K Bauri¹, Sabine Foro², A F M Mustafizur Rahman³

Affiliations

¹ Bio-Organic Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
² Institute of Materials Science, Darmstadt University of Technology, Alarich-Weiss-Strasse 2, D-64287 Darmstadt, Germany.
³ Department of Applied Chemistry & Chemical Engineering, University of Dhaka, Dhaka, Dhaka-1000, Bangladesh.

Abstract

The title compound, C₁₄H₁₃BrO₃ [systematic name: rac-(9S,10R)-9-bromo-10-hy-droxy-8,8-dimethyl-9,10-di-hydro-2H,8H-pyrano[2,3-f]chromen-2-one], is a substituted pyran-ocoumarin, obtained by bromination of seselin [8,8-dimethyl-2H,8H-pyrano[2,3-f]chromen-2-one], which was isolated from the Indian herb Trachyspermum stictocarpum (Aajmod). The pyrano ring has a distorted half-chair conformation and its mean plane is inclined to the coumarin mean plane by 1.6 (2)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers with an R²₂(16) ring motif. The dimers stack along the a-axis direction and are linked by offset π-π inter-actions, forming columns [inter-centroid distance = 3.514 (4) Å].

Keywords: bromination; crystal structure; hydrogen bonding; offset π–π interactions; seselin.