(S)-6-Chloro-4-cyclo-propyl-ethynyl-4-trifluoro-methyl-1H-3,1-benzoxazin-2(4H)-one
Abstract:
Two independent mol-ecules comprise the crystallographic asymmetric unit in the title anti-retroviral agent Efavirenz, C(14)H(9)ClF(3)NO(2), and these have noteworthy differences in conformation. The major difference relates to the orientation of the 2-cyclo-propyl-ethynyl residue relative to the six-membered heterocycle: this approaches an orthogonal disposition in mol-ecule a compared to a more flattened conformation in mol-ecule b, the difference being reflected in the O(ring)-C-C-C(ethyne) torsion angles of 65 (4) and 159 (5)°, respectively. The independent mol-ecules are connected via the eight-membered {⋯HNC (O)}(2) amide synthon. Disorder is noted in the cyclo-propane ring of mol-ecule b in that two orientations of equal weight were discerned.
More Related Videos
Related Concept Videos
Nomenclature of Aromatic Compounds with Multiple Substituents
For disubstituted benzene derivatives, with two groups attached to the benzene ring, three constitutional isomers are possible. For example, consider dimethyl benzene, often called xylene, where the second methyl group can be substituted at the second, third, or fourth carbon. The relative position of the substituents is represented by prefixes ortho, meta, or...
Alkyl Halides
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
Naming Enantiomers
Disubstituted Cyclohexanes: cis-trans Isomerism
In cyclohexane, the substituents can occupy different positions generating distinct isomers.
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Prochirality

![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)
