A series of chalcones and their derivatives have been synthesized. Chalcones, 1-(1,3-benzodioxol-5-yl)-3-(aryl)-prop-2-en-1-ones were prepared by the aldol condensation of 1-(1,3-benzodioxol-5-yl)ethanones and aryl aldehydes. Based-catalyzed condensation of 1-(1,3-benzodioxol-5-yl)-3-(aryl)prop-2-en-1-ones with ethyl acetoacetate yields corresponding ethyl 4-(1,3-benzodioxol-5-yl)-6-(aryl)-2-oxocyclohex-3-ene-1-carboxylates. Some of the synthesized chalcones were reported in the literature; the newly synthesized compounds were characterized by single crystal X-ray studies, IR, 1 H-NMR and LCMS mass spectral analysis.

Key indicatorsSingle-crystal X-ray study T = 173 K Mean (C-C) = 0.002 Å R factor = 0.040 wR factor = 0.106 Data-to-parameter ratio = 13.9For details of how these key indicators were automatically derived from the article, see

Key indicators: single-crystal X-ray study; T = 295 K; mean (C-C) = 0.002 Å; R factor = 0.029; wR factor = 0.075; data-to-parameter ratio = 18.5. organic compounds o3248 # 2007 International Union of Crystallography

Key indicators: single-crystal X-ray study; T = 291 K; mean (C-C) = 0.002 Å; R factor = 0.042; wR factor = 0.120; data-to-parameter ratio = 14.7. The title compound, C 15 H 15 N 4 O + ÁC 6 H 2 N 3 O 7 À , is the picrate salt of nevirapine, in which the cation and anion are linked by an N-HÁ Á ÁO hydrogen bond. A second N-HÁ Á ÁO interaction leads to centrosymmetric dimers of cations. The dihedral angle between the aromatic ring planes in the cation is 48.27 (8) . Experimental Crystal data C 15 H 15 N 4 O + ÁC 6 H 2 N 3 O 7 À M r = 495.42 Triclinic, P1 a = 9.9921 (5) Å b = 10.2126 (5) Å c = 11.5332 (6) Å = 70.716 (1) = 77.980 (1) = 87.355 (1) V = 1086.19 (9) Å 3 Z = 2 Mo K radiation = 0.12 mm À1 T = 291 (2) K 0.40 Â 0.30 Â 0.24 mm Data collection Bruker SMART 1000 CCD diffractometer Absorption correction: multi-scan (SADABS; Bruker, 1999) T min = 0.955, T max = 0.972 8228 measured reflections 4911 independent reflections 3575 reflections with I > 2(I) R int = 0.015

Tthe structure of the title compound, C15H24O5, has been redetermined at 103 (2) K, with much improved precision. The title compound was first reported by Luo, Yeh, Brossi, Flippen-Anderson & Gillardi [Helv. Chim. Acta (1984). 67, 1515–1522]. It is a derivative of the anti­malaria compound artemisinin and consists primarily of three substituted ring systems fused together. A cyclo­hexane ring (with a distorted chair conformation), is fused to a tetra­hydro­pyran group (also with a distorted chair conformation), and is adjacent to an oxacyclo­heptane unit containing an endoperoxide bridge. This gives the mol­ecule a unique three-dimensional arrangement. The crystal packing is stabilized by inter­molecular C–H⋯O and O–H⋯O inter­actions between an H atom from the cyclo­hexane ring and an O atom from the endoperoxide bridge, as well as between the hydroxyl H atom and an O atom from a tetra­hydro­pyran ring.