5-Hydroxy-7-phenyl-5-(prop-2-yn-1-yl)-5,6-dihydro-1-benzofuran-2(4H)-one monohydrate

In the title compound, C17H14O3·H2O, the six-membered ring, which adopts a half-chair conformation, makes a dihedral angle of 24.3 (2)° with the phenyl ring. In the crystal, the components are linked by O—H⋯O hydrogen bonds involving the water molecule, and the hydroxy and carbonyl groups of the organic compound. These interactions form a square-like supramolecular synthon unit which propagates as chains parallel to the crystallographic b axis. A C—H⋯O interaction also occurs.

In the title compound, C 17 H 14 O 3 ÁH 2 O, the six-membered ring, which adopts a half-chair conformation, makes a dihedral angle of 24.3 (2) with the phenyl ring. In the crystal, the components are linked by O-HÁ Á ÁO hydrogen bonds involving the water molecule, and the hydroxy and carbonyl groups of the organic compound. These interactions form a square-like supramolecular synthon unit which propagates as chains parallel to the crystallographic b axis. A C-HÁ Á ÁO interaction also occurs.   Table 1 Hydrogen-bond geometry (Å , ). Financial support from the Spanish Ministerio de Educacion y Ciencia (MAT2006-01997 and 'Factoría de Cristalizació n' Consolider Ingenio 2010) and FEDER funding is acknowledged.

Related literature
Comment 2-Butenolides are ubiquitous chemical moieties found in many natural products coming from plants, microorganisms and algae. A range of synthetic approaches to this class of compounds exists and includes among others, palladium-catalyzed cross-coupling reaction between allenoic acids and 2,3-allenols (Ma et al., 2005), gold-catalyzed Z-enynol cyclization (Liu et al., 2006) or ring-closing metathesis of methallyl acrylates (Bassetti et al., 2005). However, only a few multicomponent methods have been reported that include a Passerini reaction (Beck et al., 2001) and Fischer carbene complexes (Rudler et al., 2004) among others. In this context, a new multicomponent method for the synthesis of bicyclic 2-butenolides through the coupling of imide lithium enolates, propargylic organometallics and Fischer carbene complexes will be soon published elsewhere.
The molecular structure of the title compound is shown in Fig. 1. The molecular packing is dominated by three main hydrogen bonds O10-H10···O21, O21-H21A···O10 i and O21-H21B···O14 ii involving the water molecule, and the hydroxyl and carbonyl groups of the compound. These interactions involving two compounds and two water molecules form a square-like supramolecular synthon unit which propagates as linear chains parallel to the crystallographic b axis.
Experimental n-Butyllithium (1.2 mmol, 1.6 M in hexane, 750 µL) was added to a stirred solution of diisopropylamine (1.2 mmol, 172 µL) in THF (2 ml) at 273 K. After stirring for 15 min at 273 K, the solution was cooled to 195 K and 3-acetyl-2-oxazolidinone (1.2 mmol, 155 mg) in THF (2 ml) was added dropwise over 5 min. The mixture was stirred at 195 K for a further 30 min period to complete the formation of the lithium enolate. Pentacarbonyl-(1-methoxy-1-phenylmethylene)chromium (1 mmol, 312 mg) in THF (20 ml) was added over the lithium enolate solution at 195 K and the resulting mixture was stirred for 15 min. After that, propargylmagnesium bromide (2.6 mmol, 0.5 M in Et 2 O, 5.2 ml) was added dropwise at 195 K. The mixture was stirred for 30 min at 195 K and then for 12 h at 218 K. Then it was allowed to reach 293 K slowly (8 h). The reaction was quenched with NH 4 Cl (20 ml, saturated aqueous solution), diluted with hexane/ethyl acetate, 10/1 (110 ml) and subjected to air oxidation under sunlight. After 24 h, the yellow suspension was filtered through Celite and extracted with diethyl ether (3 x 10 ml). The organic layers were combined, dried over anhydrous Na 2 SO 4 and concentrated in vacuo.
The crude product was purified by flash column chromatography on silica gel using mixtures of hexane/ethyl acetate (20/1 to 9/1 to 3/1 to 1/1) to yield the title compound (0.68 mmol, 181 mg, 68%) as a pure compound.

Refinement
All non-H atoms were anisotropically refined. All H atoms were placed in geometrically idealized positions with C-H ride on their parent atoms with U iso (H) = 1.2*U eq (C) and U iso (H) = 1.5*U eq (O), except for the water H atoms which were isotropically refined. Fig. 1. Perspective view of the title compound. Displacement ellipsoids are drawn at the 50% probability level.