I. INTRODUCTION
Benzofuran and dihydrobenzofuran derivatives are natural and synthetic medicinally important heterocyclic molecules (Benavides et al., Reference Benavides, Sartorelli and Kato1999; Apers et al., Reference Apers, Vlietinck and Pieters2003). The chemistry of these compounds has been very interesting for organic chemists, owing to the presence of scaffolds on the skeletons of numerous natural products and pharmaceutical agents (Tsai et al., Reference Tsai, Hsieh and Duh1998; Chen et al., Reference Chen, Shaw, Chen and Tsai2002). A large number of reports have shown that these compounds exhibit a broad spectrum with potential bioactivities, such as antiplasmodial (Rakotondramanana et al., Reference Rakotondramanana, Delomenède, Baltas, Duran, Bedos-Belval, Rasoanaivo, Negre-Salvayre and Gornitzka2007), antileishmanial (Van Miert et al., Reference Van Miert, Van Dyck, Schmidt, Brun, Vlietinck, Lemière and Pieters2005), antimicrobial (Kossakowski et al., Reference Kossakowski, Ostrowska, Struga and Stefanska2009) and anti-inflammatory (Wu et al., Reference Wu, Chang, Wang, Hwang, Lee, Chen, Wu and Wu2011). In general, many synthetic methods for the synthesis of (dihydro)benzofuran systems have been developed (Bertolini and Pineschi, Reference Bertolini and Pineschi2009). Among them, the Lewis acid-promoted formal [3 + 2] cycloaddition reaction is a powerful and successful synthetic tool to rapidly construct this ring system (Engler et al., Reference Engler, Wei, Letavic, Combrink and Reddy1994, Reference Engler, Meduna, LaTessa and Chai1996; Engler and Lyenyar, Reference Engler and Lyenyar1998). Interesting chemical transformation with propenylbenzenes is this cycloaddition catalyzed by Fe(ClO4)3 (Ohara et al., Reference Ohara, Kiyokane and Itoh2002, Reference Ohara, Kawai, Hayase and Itoh2003), InCl3 (Yadav et al., Reference Yadav, Reddy and Kondaji2003) for obtaining the trans-2,3-dihydrobenzo[b]furan-5-ols derivatives have been reported. We have also described the diastereoselective synthesis of corresponding trans-2-(4-methoxyphenyl)-3-methyl-2,3-dihydrobenzo[b]furan-5-ol (1) using BF3.OEt2 as catalyst and PEG-400 as a green and reusable solvent (Kouznetsov et al., Reference Kouznetsov, Merchan and Romero2008). However, few crystallographic studies by X-ray diffraction (XRD) of this type of derivative have been reported.
In this regard, our ongoing research program focused on the bioactive dihydrobenzofuran derivatives with anethole fragments and its X-ray crystallographic study. Here, we discuss a simple methodology for preparation of compound 5-acryloyloxy-trans-2-(4-methoxiphenyl)-3-methyl-2,3-dihydrobenzo[b]furan (2) through the acryloylation reaction starting from the corresponding 2,3-dihydrobenzo[b]furan-5-ol (1) and report the results of the molecular characterization (FT-IR, GC-MS, 1H-NMR and 13C-NMR) and X-ray powder diffraction (XRPD) data.
II. EXPERIMENTAL
A. Synthesis
As shown in Figure 1, the title compound was synthesized as follows: a mixture of trans-2-(4-methoxyphenyl)-3-methyl-2,3-dihydrobenzo[b]furan-5-ol (1) (0.50 g, 1.95 mmol) and triethylamine (0.39 g, 3.91 mmol) in CH2Cl2 (30 ml) was stirred at room temperature, after 10 min the system was cooled to 0 °C and a solution of acryloyl chloride (0.35 g, 3.91 mmol) was added dropwise via syringe for 5 min into the mixture. The resulting mixture was stirred vigorously at room temperature overnight (about 14–16 h). After completion of the reaction as indicated by Thin Layer Chromatography (TLC), the final reaction mixture was placed at 0 °C and was carefully diluted with water (20 ml) and extracted with dichloromethane (3 × 15 ml). The organic layer was separated and dried (Na2SO4), concentrated in vacuo and the crude product was purified by column chromatography using silica gel (60–120 mesh) and eluted with petroleum ether – ethyl acetate to afford pure dihydrobenzofuran (2) (yield 82%). The melting point was between 99 and 101 °C.

Figure 1. Synthesis of the 5-acryloyloxy-trans-2-(4-methoxiphenyl)-3-methyl-2,3-dihydrobenzo[b]furan (2) via acryloylation reaction.
The molecular characterization that was carried out with infrared (IR) spectrometry showed the following characteristic signals: 3007, 2953, 2884, 1734, 1610 and 1515 cm−1; Mass Spectrometry (MS) gave a molecular peak m/z = 310 (60, M +); nuclear magnetic resonance on protons 1H NMR (400 MHz, CDCl3 Me4Si) showed δ (ppm) to be 1.39 (3H, d, J = 6.8 Hz, −CH3), 3.47 (1H, m, 3-H), 3.82 (3H, s, CH3O-Ar), 5.15 (1H, d, J = 9.3 Hz, 2-H), 6.00 (1H, dd, J = 9.3, 1.1 Hz, Hvinyl), 6.33 (1H, dd, J = 17.3, 10.4 Hz, Hvinyl), 6.61 (1H, dd, J = 17.3, 1.1 Hz, Hvinyl), 6.83 (1H, d, J = 8.3 Hz, 6-H), 6.92 (4H, m, 4-H, 7-H y 2-HAr) and 7.37 (2H, d, J = 8.6 Hz, 3-HAr); nuclear magnetic resonance on carbons 13C-NMR (100 Hz, CDCl3 Me4Si), δ (ppm), presents the following data: 165.1, 159.7, 156.8, 144.4, 133.1, 132.2, 132.2, 128.0, 127.6 (2C), 120.9, 117.0, 114.0 (2C), 109.5, 93.0, 55.2, 45.4, and 17.4.
B. Powder data collection
The title compound was ground and sieved to grain size less than 38 µm. The compound was mounted on a zero-background specimen holder. The diffraction pattern was collected at room temperature (298 K) in the 2θ range from 2 to 70° 2θ with a step size of 0.02° 2θ and a count time of 0.4 s per step, using a D8 FOCUS BRUKER diffractometer operating in Bragg–Brentano geometry quipped with an X-ray tube (CuKα radiation: λ = 1.5406 Å, 40 kV and 40 mA) with a nickel filter and a one-dimensional LynxEye detector. A fixed anti-scatter slit of 8 mm, receiving slit of 1 mm, soller slits of 2.5° and a detector slit of 3 mm were used.
PowderX program (Dong, Reference Dong1999) was used to remove the background (Sonneveld and Visser, Reference Sonneveld and Visser1975), smoothing (Savitzky and Golay, Reference Savitzky and Golay1964), to eliminate the Kα 2 component (Rachinger, Reference Rachinger1948) and the second derivative method was used to determine the peak observed positions and intensities.
III. RESULTS AND DISCUSSION
The experimental XRPD pattern is depicted in Figure 2. XRPD data for the title compound are given in Table I. Indexing of the experimental XRPD pattern was done using the DICVOL06 program (Boultif and Louër, Reference Boultif and Loüer2006) with an absolute error of 0.03° 2θ. The title compound crystallized in a monoclinic system with space group P21/c (No. 14) estimated by the CHEKCELL program (Laugier and Bochu, Reference Laugier and Bochu2002), which was compatible with the systematic absence and with the crystal density (1.447 g cm−3). The unit-cell parameters were refined with the NBS*AIDS83 program (Mighell et al., Reference Mighell, Hubberd and Stalick1981). Unit-cell data, values of M 20 (de Wolff, Reference de Wolff1968) and F 30 (Smith and Snyder, Reference Smith and Snyder1979) are presented in Table II.

Figure 2. XRPD pattern of 5-acryloyloxy-trans-2-(4-methoxiphenyl)-3-methyl-2,3-dihydrobenzo[b]furan (2).
TABLE I. XRPD data of 5-acryloyloxy-trans-2-(4-methoxiphenyl)-3-methyl-2,3-dihydrobenzo[b]furan (2).

Table II. Crystal-structure data for 5-acryloyloxy-trans-2-(4-methoxiphenyl)-3-methyl-2,3-dihydrobenzo[b]furan (2).

ACKNOWLEDGEMENTS
This work was supported by grant RC-245-2011 Colciencias (Patrimonio Autónomo del Fondo Nacional de Financiamiento para la Ciencia, la Tecnología y la Innovación, Francisco José de Caldas). The authors would like to acknowledge Miguel A. Ramos from the Instituto Zuliano de Investigaciones Tecnológicas, INZIT (Maracaibo-Venezuela) for data collection. Arnold R. Romero Bohórquez thanks COLCIENCIAS for the PhD fellowship studies (2005–2010). Mónica V. Sandoval thanks COLCIENCIAS and the Universidad Industrial de Santander for the scholarship (Programa Jóvenes Investigadores e Innovadores año 2010).