Related literature {#sec1}
==================

For the crystal structures of similar alkyl 2-\[5-(4-hydroxy­phen­yl)-3-methyl­sulfanyl-1-benzofuran-2-yl\]acetate derivatives, see: Choi *et al.* (2006[@bb4], 2009[@bb5]). For the pharmacological activity of benzofuran compounds, see: Howlett *et al.* (1999[@bb7]); Twyman & Allsop (1999[@bb11]). For natural products involving a benzofuran ring, see: Akgul & Anil (2003[@bb1]); von Reuss & König (2004[@bb8]).

Experimental {#sec2}
============

 {#sec2.1}

### Crystal data {#sec2.1.1}

C~18~H~16~O~4~S*M* *~r~* = 328.37Monoclinic,*a* = 13.6661 (6) Å*b* = 7.6643 (3) Å*c* = 15.6344 (7) Åβ = 95.4731 (6)°*V* = 1630.10 (12) Å^3^*Z* = 4Mo *K*α radiationμ = 0.22 mm^−1^*T* = 173 K0.45 × 0.25 × 0.25 mm

### Data collection {#sec2.1.2}

Bruker SMART CCD diffractometerAbsorption correction: multi-scan (*SADABS*; Sheldrick, 2000[@bb9]) *T* ~min~ = 0.940, *T* ~max~ = 0.96113917 measured reflections3703 independent reflections2894 reflections with *I* \> 2σ(*I*)*R* ~int~ = 0.046

### Refinement {#sec2.1.3}

*R*\[*F* ^2^ \> 2σ(*F* ^2^)\] = 0.035*wR*(*F* ^2^) = 0.097*S* = 1.083703 reflections213 parametersH atoms treated by a mixture of independent and constrained refinementΔρ~max~ = 0.30 e Å^−3^Δρ~min~ = −0.25 e Å^−3^

 {#d5e468}

Data collection: *SMART* (Bruker, 2001[@bb3]); cell refinement: *SAINT* (Bruker, 2001[@bb3]); data reduction: *SAINT*; program(s) used to solve structure: *SHELXS97* (Sheldrick, 2008[@bb10]); program(s) used to refine structure: *SHELXL97* (Sheldrick, 2008[@bb10]); molecular graphics: *ORTEP-3* (Farrugia, 1997[@bb6]) and *DIAMOND* (Brandenburg, 1998[@bb2]); software used to prepare material for publication: *SHELXL97*.

Supplementary Material
======================

Crystal structure: contains datablocks global, I. DOI: [10.1107/S1600536809037763/si2201sup1.cif](http://dx.doi.org/10.1107/S1600536809037763/si2201sup1.cif)

Structure factors: contains datablocks I. DOI: [10.1107/S1600536809037763/si2201Isup2.hkl](http://dx.doi.org/10.1107/S1600536809037763/si2201Isup2.hkl)

Additional supplementary materials: [crystallographic information](http://scripts.iucr.org/cgi-bin/sendsupfiles?si2201&file=si2201sup0.html&mime=text/html); [3D view](http://scripts.iucr.org/cgi-bin/sendcif?si2201sup1&Qmime=cif); [checkCIF report](http://scripts.iucr.org/cgi-bin/paper?si2201&checkcif=yes)

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: [SI2201](http://scripts.iucr.org/cgi-bin/sendsup?si2201)).

Comment
=======

Benzofuran ring systems have received considerable interest in view of their pharmacological properties (Howlett *et al.*, 1999; Twyman & Allsop, 1999), and these compounds are occurring in natural products (Akgul & Anil, 2003; von Reuss & König, 2004). As a part of our ongoing studies of the effect of side chain substituents on the solid state structures of alkyl 2-\[5-(4-hydroxyphenyl)-3-methylsulfanyl-1-benzofuran-2-yl\]acetate analogues (Choi *et al.*, 2006, 2009), we report the crystal structure of the title compound (Fig. 1).

The benzofuran unit is essentially planar, with a mean deviation of 0.005 (1) Å from the least-squares plane defined by the nine constituent atoms. The 4-hydroxyphenyl ring is rotated out of the benzofuran plane, making a dihedral angle of 34.52 (6)°. The methyl group of the methylsulfanyl substituent is tilted towards the plane of the benzofuran unit \[100.90 (8)°\]. The molecular packing (Fig. 2) is stabilized by intermolecular O---H···O hydrogen bonds between the hydroxy H atom and the oxygen of the C═O unit, with a O4---H4···O3^i^ (Table 1). The crystal packing (Fig. 2) is further stabilized by intermolecular C---H···π interactions between the methyl H atom of the methylsulfanyl substituent and the 4-hydroxyphenyl ring, with a C18---H18C···Cg^ii^ (Table 1; Cg is the centroid of the C12--C17 phenyl ring).

Experimental {#experimental}
============

2-\[5-(4-Hydroxyphenyl)-3-methylsulfanyl-1-benzofuran-2-yl\]acetic acid (471 mg, 1.5 mmol) was added to a solution of concentrated sulfuric acid (3 drops) in methanol (20 ml), and the mixture was refluxed for 6h, then cooled. The solvent was evaporated and the residue was poured into water. The mixture was extracted with dichloromethane, dried over magnesium sulfate, filtered and concentrated under vacuum. The residue was purified by column chromatography (benzene--acetone, 9 : 1 v/v) to afford the title compound as a colorless solid \[yield 88%, m.p. 446--447 K; *R*~f~ = 0.49 (benzene--acetone, 9 : 1 v/v)\]. Single crystals suitable for X-ray diffraction were prepared by evaporation of a solution of the title compound in benzene at room temperature.

Refinement {#refinement}
==========

The hydroxy H atom was found in a difference Fourier map and refined freely. The other H atoms were positioned geometrically and refined using a riding model, with C---H = 0.93 Å for the aryl, 0.97 Å for the methylene, and 0.96 Å for the methyl H atoms. *U*~iso~(H) = 1.2*U*~eq~(C) for the aryl and methylene H atoms, and 1.5*U*~eq~(C) for methyl H atoms.

Figures
=======

![The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as a small cycles of arbitrary radius.](e-65-o2529-fig1){#Fap1}

![O--H···O and C---H···π interactions (dotted lines) in the title compound. Cg denotes the ring centroid. \[Symmetry codes: (i) - x + 1, y + 1, - z + 3/2; (ii) - x + 1, - y + 1, - z + 1; (iii) - x + 1, y - 1/2, - z + 3/2.\]](e-65-o2529-fig2){#Fap2}

Crystal data {#tablewrapcrystaldatalong}
============

  ------------------------- ---------------------------------------
  C~18~H~16~O~4~S           *F*(000) = 688
  *M~r~* = 328.37           *D*~x~ = 1.338 Mg m^−3^
  Monoclinic, *P*2~1~/*c*   Mo *K*α radiation, λ = 0.71073 Å
  Hall symbol: -P 2ybc      Cell parameters from 6226 reflections
  *a* = 13.6661 (6) Å       θ = 2.6--27.3°
  *b* = 7.6643 (3) Å        µ = 0.22 mm^−1^
  *c* = 15.6344 (7) Å       *T* = 173 K
  β = 95.4731 (6)°          Block, colorless
  *V* = 1630.10 (12) Å^3^   0.45 × 0.25 × 0.25 mm
  *Z* = 4                   
  ------------------------- ---------------------------------------

Data collection {#tablewrapdatacollectionlong}
===============

  --------------------------------------------------------------- --------------------------------------
  Bruker SMART CCD diffractometer                                 3703 independent reflections
  Radiation source: fine-focus sealed tube                        2894 reflections with *I* \> 2σ(*I*)
  graphite                                                        *R*~int~ = 0.046
  Detector resolution: 10.0 pixels mm^-1^                         θ~max~ = 27.5°, θ~min~ = 1.5°
  φ and ω scans                                                   *h* = −17→17
  Absorption correction: multi-scan (*SADABS*; Sheldrick, 2000)   *k* = −9→9
  *T*~min~ = 0.940, *T*~max~ = 0.961                              *l* = −20→20
  13917 measured reflections                                      
  --------------------------------------------------------------- --------------------------------------

Refinement {#tablewraprefinementdatalong}
==========

  ------------------------------------- -----------------------------------------------------------------------------------------------
  Refinement on *F*^2^                  Primary atom site location: structure-invariant direct methods
  Least-squares matrix: full            Secondary atom site location: difference Fourier map
  *R*\[*F*^2^ \> 2σ(*F*^2^)\] = 0.035   Hydrogen site location: difference Fourier map
  *wR*(*F*^2^) = 0.097                  H atoms treated by a mixture of independent and constrained refinement
  *S* = 1.08                            *w* = 1/\[σ^2^(*F*~o~^2^) + (0.038*P*)^2^ + 0.664*P*\] where *P* = (*F*~o~^2^ + 2*F*~c~^2^)/3
  3703 reflections                      (Δ/σ)~max~ \< 0.001
  213 parameters                        Δρ~max~ = 0.30 e Å^−3^
  0 restraints                          Δρ~min~ = −0.25 e Å^−3^
  ------------------------------------- -----------------------------------------------------------------------------------------------

Special details {#specialdetails}
===============

  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
  Refinement. Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ \> 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.
  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å^2^) {#tablewrapcoords}
==================================================================================================

  ------ -------------- -------------- -------------- -------------------- --
         *x*            *y*            *z*            *U*~iso~\*/*U*~eq~   
  S1     0.69956 (3)    0.01335 (5)    0.51042 (3)    0.02878 (12)         
  O1     0.80580 (8)    0.44720 (15)   0.62041 (7)    0.0290 (3)           
  O2     1.05303 (8)    0.08785 (16)   0.60370 (7)    0.0330 (3)           
  O3     0.94920 (8)    0.15452 (18)   0.70121 (8)    0.0379 (3)           
  O4     0.09318 (9)    0.48769 (18)   0.64861 (9)    0.0377 (3)           
  H4     0.0789 (17)    0.535 (3)      0.6922 (17)    0.061 (8)\*          
  C1     0.72205 (11)   0.2164 (2)     0.55937 (9)    0.0244 (3)           
  C2     0.65254 (11)   0.33024 (19)   0.59592 (9)    0.0227 (3)           
  C3     0.55110 (11)   0.3275 (2)     0.60033 (9)    0.0229 (3)           
  H3     0.5133         0.2362         0.5759         0.027\*              
  C4     0.50698 (11)   0.4634 (2)     0.64192 (9)    0.0236 (3)           
  C5     0.56623 (11)   0.6008 (2)     0.67804 (10)   0.0277 (3)           
  H5     0.5365         0.6911         0.7057         0.033\*              
  C6     0.66711 (12)   0.6063 (2)     0.67373 (10)   0.0291 (3)           
  H6     0.7054         0.6977         0.6974         0.035\*              
  C7     0.70754 (11)   0.4684 (2)     0.63246 (10)   0.0254 (3)           
  C8     0.81116 (11)   0.2933 (2)     0.57520 (10)   0.0268 (3)           
  C9     0.91070 (11)   0.2406 (2)     0.55381 (10)   0.0289 (3)           
  H9A    0.9450         0.3428         0.5354         0.035\*              
  H9B    0.9040         0.1591         0.5062         0.035\*              
  C10    0.97139 (11)   0.1573 (2)     0.62834 (10)   0.0266 (3)           
  C11    1.11920 (14)   0.0120 (3)     0.67179 (13)   0.0460 (5)           
  H11A   1.0857         −0.0787        0.6997         0.055\*              
  H11B   1.1403         0.1006         0.7129         0.055\*              
  H11C   1.1754         −0.0362        0.6478         0.055\*              
  C12    0.39861 (11)   0.46601 (19)   0.64631 (10)   0.0227 (3)           
  C13    0.33451 (11)   0.4013 (2)     0.57879 (10)   0.0246 (3)           
  H13    0.3604         0.3531         0.5312         0.030\*              
  C14    0.23358 (12)   0.4071 (2)     0.58084 (10)   0.0272 (3)           
  H14    0.1925         0.3618         0.5354         0.033\*              
  C15    0.19364 (11)   0.4809 (2)     0.65104 (10)   0.0267 (3)           
  C16    0.25574 (12)   0.5440 (2)     0.71976 (10)   0.0289 (3)           
  H16    0.2296         0.5919         0.7673         0.035\*              
  C17    0.35686 (12)   0.5352 (2)     0.71715 (10)   0.0273 (3)           
  H17    0.3979         0.5765         0.7637         0.033\*              
  C18    0.62715 (13)   0.0771 (2)     0.41243 (12)   0.0365 (4)           
  H18A   0.5645         0.1201         0.4260         0.055\*              
  H18B   0.6176         −0.0220        0.3750         0.055\*              
  H18C   0.6610         0.1671         0.3843         0.055\*              
  ------ -------------- -------------- -------------- -------------------- --

Atomic displacement parameters (Å^2^) {#tablewrapadps}
=====================================

  ----- ------------- ------------- ------------- -------------- -------------- ---------------
        *U*^11^       *U*^22^       *U*^33^       *U*^12^        *U*^13^        *U*^23^
  S1    0.0320 (2)    0.0222 (2)    0.0323 (2)    0.00435 (16)   0.00399 (16)   −0.00155 (16)
  O1    0.0219 (5)    0.0333 (6)    0.0313 (6)    0.0002 (5)     0.0002 (4)     −0.0056 (5)
  O2    0.0240 (6)    0.0455 (7)    0.0299 (6)    0.0094 (5)     0.0041 (4)     0.0007 (5)
  O3    0.0297 (6)    0.0546 (8)    0.0309 (6)    0.0048 (6)     0.0105 (5)     0.0091 (6)
  O4    0.0244 (6)    0.0501 (8)    0.0394 (7)    −0.0021 (5)    0.0082 (5)     −0.0150 (6)
  C1    0.0250 (8)    0.0242 (7)    0.0241 (7)    0.0036 (6)     0.0028 (6)     0.0005 (6)
  C2    0.0246 (7)    0.0218 (7)    0.0218 (7)    0.0030 (6)     0.0023 (6)     0.0008 (6)
  C3    0.0238 (7)    0.0210 (7)    0.0239 (7)    0.0001 (6)     0.0020 (6)     −0.0002 (6)
  C4    0.0253 (7)    0.0241 (8)    0.0212 (7)    0.0030 (6)     0.0011 (6)     0.0011 (6)
  C5    0.0279 (8)    0.0268 (8)    0.0277 (8)    0.0059 (6)     −0.0004 (6)    −0.0059 (6)
  C6    0.0299 (8)    0.0275 (8)    0.0289 (8)    −0.0013 (7)    −0.0031 (6)    −0.0064 (6)
  C7    0.0210 (7)    0.0300 (8)    0.0246 (8)    0.0020 (6)     −0.0006 (6)    −0.0003 (6)
  C8    0.0259 (8)    0.0305 (8)    0.0240 (7)    0.0033 (6)     0.0019 (6)     −0.0001 (6)
  C9    0.0227 (8)    0.0370 (9)    0.0274 (8)    0.0022 (7)     0.0039 (6)     0.0001 (7)
  C10   0.0204 (7)    0.0295 (8)    0.0304 (8)    −0.0025 (6)    0.0055 (6)     −0.0002 (6)
  C11   0.0311 (9)    0.0670 (14)   0.0392 (10)   0.0158 (9)     0.0007 (8)     0.0111 (10)
  C12   0.0255 (7)    0.0190 (7)    0.0238 (7)    0.0035 (6)     0.0033 (6)     0.0010 (6)
  C13   0.0290 (8)    0.0223 (7)    0.0232 (7)    0.0026 (6)     0.0061 (6)     −0.0021 (6)
  C14   0.0279 (8)    0.0276 (8)    0.0257 (8)    −0.0010 (6)    0.0006 (6)     −0.0038 (6)
  C15   0.0240 (7)    0.0268 (8)    0.0299 (8)    0.0001 (6)     0.0057 (6)     −0.0007 (6)
  C16   0.0311 (8)    0.0314 (8)    0.0252 (8)    0.0018 (7)     0.0080 (6)     −0.0054 (7)
  C17   0.0295 (8)    0.0284 (8)    0.0239 (8)    0.0017 (6)     0.0015 (6)     −0.0039 (6)
  C18   0.0385 (10)   0.0337 (9)    0.0361 (9)    0.0017 (8)     −0.0020 (7)    −0.0023 (7)
  ----- ------------- ------------- ------------- -------------- -------------- ---------------

Geometric parameters (Å, °) {#tablewrapgeomlong}
===========================

  -------------------- -------------- ----------------------- --------------
  S1---C1              1.7488 (16)    C8---C9                 1.487 (2)
  S1---C18             1.8099 (18)    C9---C10                1.506 (2)
  O1---C8              1.3810 (19)    C9---H9A                0.9700
  O1---C7              1.3833 (18)    C9---H9B                0.9700
  O2---C10             1.3260 (18)    C11---H11A              0.9600
  O2---C11             1.451 (2)      C11---H11B              0.9600
  O3---C10             1.2067 (19)    C11---H11C              0.9600
  O4---C15             1.3708 (19)    C12---C13               1.397 (2)
  O4---H4              0.81 (3)       C12---C17               1.398 (2)
  C1---C8              1.354 (2)      C13---C14               1.383 (2)
  C1---C2              1.447 (2)      C13---H13               0.9300
  C2---C7              1.390 (2)      C14---C15               1.392 (2)
  C2---C3              1.395 (2)      C14---H14               0.9300
  C3---C4              1.395 (2)      C15---C16               1.391 (2)
  C3---H3              0.9300         C16---C17               1.388 (2)
  C4---C5              1.413 (2)      C16---H16               0.9300
  C4---C12             1.489 (2)      C17---H17               0.9300
  C5---C6              1.387 (2)      C18---H18A              0.9600
  C5---H5              0.9300         C18---H18B              0.9600
  C6---C7              1.380 (2)      C18---H18C              0.9600
  C6---H6              0.9300                                 
                                                              
  C1---S1---C18        100.90 (8)     O3---C10---O2           124.16 (15)
  C8---O1---C7         105.64 (12)    O3---C10---C9           124.63 (14)
  C10---O2---C11       115.50 (13)    O2---C10---C9           111.21 (13)
  C15---O4---H4        108.3 (17)     O2---C11---H11A         109.5
  C8---C1---C2         106.18 (14)    O2---C11---H11B         109.5
  C8---C1---S1         125.76 (12)    H11A---C11---H11B       109.5
  C2---C1---S1         127.94 (12)    O2---C11---H11C         109.5
  C7---C2---C3         119.49 (14)    H11A---C11---H11C       109.5
  C7---C2---C1         105.79 (13)    H11B---C11---H11C       109.5
  C3---C2---C1         134.71 (14)    C13---C12---C17         117.36 (14)
  C2---C3---C4         119.18 (14)    C13---C12---C4          121.01 (13)
  C2---C3---H3         120.4          C17---C12---C4          121.63 (14)
  C4---C3---H3         120.4          C14---C13---C12         121.72 (14)
  C3---C4---C5         119.09 (14)    C14---C13---H13         119.1
  C3---C4---C12        120.49 (14)    C12---C13---H13         119.1
  C5---C4---C12        120.41 (13)    C13---C14---C15         119.89 (14)
  C6---C5---C4         122.50 (14)    C13---C14---H14         120.1
  C6---C5---H5         118.8          C15---C14---H14         120.1
  C4---C5---H5         118.8          O4---C15---C16          122.95 (14)
  C7---C6---C5         116.33 (15)    O4---C15---C14          117.44 (14)
  C7---C6---H6         121.8          C16---C15---C14         119.61 (14)
  C5---C6---H6         121.8          C17---C16---C15         119.76 (14)
  C6---C7---O1         126.20 (14)    C17---C16---H16         120.1
  C6---C7---C2         123.41 (14)    C15---C16---H16         120.1
  O1---C7---C2         110.39 (13)    C16---C17---C12         121.63 (15)
  C1---C8---O1         111.98 (13)    C16---C17---H17         119.2
  C1---C8---C9         131.83 (15)    C12---C17---H17         119.2
  O1---C8---C9         116.18 (14)    S1---C18---H18A         109.5
  C8---C9---C10        112.89 (13)    S1---C18---H18B         109.5
  C8---C9---H9A        109.0          H18A---C18---H18B       109.5
  C10---C9---H9A       109.0          S1---C18---H18C         109.5
  C8---C9---H9B        109.0          H18A---C18---H18C       109.5
  C10---C9---H9B       109.0          H18B---C18---H18C       109.5
  H9A---C9---H9B       107.8                                  
                                                              
  C18---S1---C1---C8   −114.97 (15)   S1---C1---C8---C9       3.7 (3)
  C18---S1---C1---C2   69.48 (15)     C7---O1---C8---C1       −0.77 (17)
  C8---C1---C2---C7    −0.71 (17)     C7---O1---C8---C9       179.94 (13)
  S1---C1---C2---C7    175.53 (12)    C1---C8---C9---C10      −99.8 (2)
  C8---C1---C2---C3    178.91 (17)    O1---C8---C9---C10      79.33 (18)
  S1---C1---C2---C3    −4.8 (3)       C11---O2---C10---O3     −2.6 (2)
  C7---C2---C3---C4    −0.4 (2)       C11---O2---C10---C9     176.96 (15)
  C1---C2---C3---C4    −179.96 (16)   C8---C9---C10---O3      −10.1 (2)
  C2---C3---C4---C5    0.4 (2)        C8---C9---C10---O2      170.26 (14)
  C2---C3---C4---C12   178.85 (13)    C3---C4---C12---C13     −34.2 (2)
  C3---C4---C5---C6    0.1 (2)        C5---C4---C12---C13     144.26 (15)
  C12---C4---C5---C6   −178.41 (14)   C3---C4---C12---C17     146.78 (15)
  C4---C5---C6---C7    −0.5 (2)       C5---C4---C12---C17     −34.8 (2)
  C5---C6---C7---O1    179.75 (14)    C17---C12---C13---C14   0.8 (2)
  C5---C6---C7---C2    0.5 (2)        C4---C12---C13---C14    −178.21 (14)
  C8---O1---C7---C6    −179.09 (15)   C12---C13---C14---C15   0.8 (2)
  C8---O1---C7---C2    0.28 (17)      C13---C14---C15---O4    178.18 (15)
  C3---C2---C7---C6    0.0 (2)        C13---C14---C15---C16   −1.8 (2)
  C1---C2---C7---C6    179.65 (15)    O4---C15---C16---C17    −178.96 (16)
  C3---C2---C7---O1    −179.43 (13)   C14---C15---C16---C17   1.0 (2)
  C1---C2---C7---O1    0.26 (17)      C15---C16---C17---C12   0.8 (3)
  C2---C1---C8---O1    0.92 (18)      C13---C12---C17---C16   −1.7 (2)
  S1---C1---C8---O1    −175.42 (11)   C4---C12---C17---C16    177.40 (15)
  C2---C1---C8---C9    −179.93 (16)                           
  -------------------- -------------- ----------------------- --------------

Hydrogen-bond geometry (Å, °) {#tablewraphbondslong}
=============================

  --------------------- ---------- ---------- ------------- ---------------
  *D*---H···*A*         *D*---H    H···*A*    *D*···*A*     *D*---H···*A*
  O4---H4···O3^i^       0.81 (3)   1.97 (3)   2.7826 (18)   177 (2)
  C18---H18C···Cg^ii^   0.96       2.88       3.762 (2)     153
  --------------------- ---------- ---------- ------------- ---------------

Symmetry codes: (i) −*x*+1, *y*+1/2, −*z*+3/2; (ii) −*x*+1, −*y*+1, −*z*+1.

###### Hydrogen-bond geometry (Å, °)

  *D*---H⋯*A*             *D*---H    H⋯*A*      *D*⋯*A*       *D*---H⋯*A*
  ----------------------- ---------- ---------- ------------- -------------
  O4---H4⋯O3^i^           0.81 (3)   1.97 (3)   2.7826 (18)   177 (2)
  C18---H18*C*⋯*Cg*^ii^   0.96       2.88       3.762 (2)     153

Symmetry codes: (i) ; (ii) . *Cg* is the centroid of the C12--C17 phenyl ring.
