title: Crystal and mol-ecular structure of aflatrem.
abstract: The crystal structure of the title compound, C32H39NO4, confirms the absolute configuration of the seven chiral centres in the mol-ecule. The molecule has a 1,1-dimethylprop-2-enyl substituent on the indole nucleus and this nucleus shares one edge with the five-membered ring which is, in turn, connected to a sequence of three edge-shared fused rings. The skeleton is completed by the 7,7-trimethyl-6,8-dioxabi-cyclo-[3.2.1]oct-3-en-2-one group connected to the terminal cyclohexene ring. The two cyclohexane rings adopt chair and half-chair conformations, while in the dioxabi-cyclo-[3.2.1]oct-3-en-2-one unit, the six-membered ring has a half-chair conformation. The indole system of the mol-ecule exhibits a tilt of 2.02 (1)° between its two rings. In the crystal, O-H⋯O hydrogen bonds connect mol-ecules into chains along [010]. Weak N-H⋯π inter-actions connect these chains, forming sheets parallel to (10-1).
authors.affiliation: Department of Chemistry, Higher Teacher Training College, University of Yaoundé 1, PO Box 47, Yaoundé, Cameroon.
authors.forename: Bruno N
authors.initials: BN
authors.lastname: Lenta
authors.affiliation: Department of Organic Chemistry, University of Yaoundé 1, PO Box 812, Yaoundé, Cameroon.
authors.forename: Jules
authors.initials: J
authors.lastname: Ngatchou
authors.affiliation: Department of Inorganic Chemistry, University of Yaoundé 1, PO Box 812, Yaoundé, Cameroon.
authors.forename: Patrice T
authors.initials: PT
authors.lastname: Kenfack
authors.affiliation: Department of Chemistry, University of Bielefeld, PO Box 100131, 33501 Bielefeld, Germany.
authors.forename: Beate
authors.initials: B
authors.lastname: Neumann
authors.affiliation: Department of Chemistry, University of Bielefeld, PO Box 100131, 33501 Bielefeld, Germany.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Stammler
authors.affiliation: Department of Chemistry, University of Bielefeld, PO Box 100131, 33501 Bielefeld, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Sewald
keywords: Aspergillus species; N—H⋯Cg (indole); aflatrem; crystal structure; fungal endophytes; hydrogen bonding; indole-diterpenoid