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Updated: Jun 2, 2026
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
4a-Hy-droxy-9-(2-meth-oxy-phen-yl)-4,4a,5,6,7,8,9,9a-octa-hydro-3H-xanthene-1,8(2H)-dione
Abstract:
In the title compound, C(20)H(22)O(5), an S(6) ring motif is formed by an intra-molecular C-H⋯O hydrogen bond, which contributes to the stabilization of the mol-ecule. In the xanthene system, the cyclo-hexane ring adopts a chair conformation, the cyclo-hexene ring adopts a half-boat conformation and the tetra-hydro-pyran ring adopts a half-chair conformation. The mean plane of the four essentially planar atoms of the tetra-hydro-pyran ring [r.m.s deviation = 0.092 (1) Å] forms a dihedral angle of 64.13 (6)° with the mean plane of the meth-oxy-phenyl group. In the crystal, inter-molecular O-H⋯O and weak C-H⋯O hydrogen bonds link mol-ecules into chains along the a axis, which are further stabilized by C-H⋯π inter-actions.
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