( S )-6-Chloro-4-cyclopropylethynyl-4-trifluoromethyl-1 H -3,1-benzoxazin-2(4 H )-one

Abstract

Two independent molecules comprise the crystallographic asymmetric unit in the title antiretroviral agent Efavirenz, C14H9ClF3NO2, and these have noteworthy differences in conformation. The major difference relates to the orientation of the 2-cyclopropylethynyl residue relative to the sixmembered heterocycle: this approaches an orthogonal disposition in molecule a compared to a more flattened conformation in molecule b, the difference being reflected in the Oring— C—C—Cethyne torsion angles of 65 (4) and 159 (5), respectively. The independent molecules are connected via the eightmembered { HNC (O)}2 amide synthon. Disorder is noted in the cyclopropane ring of molecule b in that two orientations of equal weight were discerned14H9ClF3NO2, and these have noteworthy differences in conformation. The major difference relates to the orientation of the 2-cyclopropylethynyl residue relative to the sixmembered heterocycle: this approaches an orthogonal disposition in molecule a compared to a more flattened conformation in molecule b, the difference being reflected in the Oring— C—C—Cethyne torsion angles of 65 (4) and 159 (5), respectively. The independent molecules are connected via the eightmembered { HNC (O)}2 amide synthon. Disorder is noted in the cyclopropane ring of molecule b in that two orientations of equal weight were discerneda compared to a more flattened conformation in molecule b, the difference being reflected in the Oring— C—C—Cethyne torsion angles of 65 (4) and 159 (5), respectively. The independent molecules are connected via the eightmembered { HNC (O)}2 amide synthon. Disorder is noted in the cyclopropane ring of molecule b in that two orientations of equal weight were discernedb, the difference being reflected in the Oring— C—C—Cethyne torsion angles of 65 (4) and 159 (5), respectively. The independent molecules are connected via the eightmembered { HNC (O)}2 amide synthon. Disorder is noted in the cyclopropane ring of molecule b in that two orientations of equal weight were discernedethyne torsion angles of 65 (4) and 159 (5), respectively. The independent molecules are connected via the eightmembered { HNC (O)}2 amide synthon. Disorder is noted in the cyclopropane ring of molecule b in that two orientations of equal weight were discernedvia the eightmembered { HNC (O)}2 amide synthon. Disorder is noted in the cyclopropane ring of molecule b in that two orientations of equal weight were discerned HNC (O)}2 amide synthon. Disorder is noted in the cyclopropane ring of molecule b in that two orientations of equal weight were discernedb in that two orientations of equal weight were discerned