3-[(R)-3,3-Dichloro-2-hydroxypropyl]-8-hydroxy-6-methoxy-1H-isochromen-1-one

The title compound, C13H12Cl2O5, is an isocoumarin compound which has been isolated from the ethyl acetate extract of the fermentation broth of actinomycete Streptomyces sp. (V4) from the South China Sea. There are intra- and intermolecular hydrogen bonds and halogen bonds [Cl⋯Cl = 3.434 (2) Å; C—Cl⋯Cl = 121.6°]. The intermolecular O—H⋯O hydrogen bonds link molecules into chains along the b axis.

The title compound, C 13 H 12 Cl 2 O 5 , is an isocoumarin compound which has been isolated from the ethyl acetate extract of the fermentation broth of actinomycete Streptomyces sp. (V 4 ) from the South China Sea. There are intra-and intermolecular hydrogen bonds and halogen bonds [ClÁ Á ÁCl = 3.434 (2) Å ; C-ClÁ Á ÁCl = 121.6 ]. The intermolecular O-HÁ Á ÁO hydrogen bonds link molecules into chains along the b axis.
Larsen et al. also reported dichlorodiaportin (Larsen & Breinholt, 1999), but it was isolated from quite different microorganism, the typical cheese-associated isolates of Penicillium nalgiovense, and its structure was only elucidated based on spectral analysis, and the absolute configuration was depicted S by comparison with the optical rotation of those reported for several analogues of known absolute configuration. However, according to the optical rotation and our crystal structure, it is clear that Larsen's compound is the same compound as our dichlorodiaportin.
We report here the crystal structure of (I). Compound (I) crystallizes in space group P 2 1 , and the 8-hydroxy-isochromen-1-one core rings in (I) is a planar conjugated ring system (Fig.1). In the crystal structure, there is an intra-molecular  Table 2).

Experimental
A strain of streptomyces sp. (V 4 ) was isolated from the South China Sea, has been deposited in the School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, P. R. China.
The filtrate was concentrated to 5L below 323 K, then extracted three times by shaking with an equal volume of ethyl acetate. The extract was evaporated under reduced pressure. The combined organic extracts were subjected to silica-gel column chromatography, eluting with petroleum ether/ethyl (1:1 v/v) acetate, to yield (I).
Colorless block crystals of (I) were obtained by evaporation of a methanol solution.

Refinement
The H atoms were positioned geometrically and were treated as riding on their parent C atoms, with C-H distances in the range of 0.93-0.98 Å, with U iso (H) = 1.2-1.5 times U eq of the parent atom. H atoms attached to O3 and O5 (hydroxyl oxygen atoms) were located in difference Fourier maps and refined initially with distance restraints of 0.82 Å with U iso (H) = 1.5 times U eq (O). Figure 1 View of the molecules in the asymmetric unit of (I), with anisotropic displacement parameters drawn at the 50% probability level.