6-[4-(tert-Butyldimethylsilyloxy)phenyl]-1-oxaspiro[2.5]heptane

In the title compound, the O atom of the epoxide group has a pseudoaxial orientation and the dihedral angle between the cyclohexyl and benzene rings is 85.80 (8)°. The C—O—Si—Ct (t = tert-butyl) torsion angle is −177.40 (14)°. In the crystal, pairwise C—H⋯O links connect the molecules into inversion dimers featuring (8) loops.


Structure description
Fumagillin and ovalicin, isolated from Aspergillus fumigatus and Pseudorotium ovalis, respectively, are sesquiterpene epoxides that exhibit anti-angiogenic activity.The key structural feature of both is a 1-oxospiro[2.5]heptanemoiety.The structure of fumagillin was initially deduced by X-ray crystallographic analysis of its hydrolysis product fumagillol (McCorkindale & Sime, 1961) and the X-ray crystal structure of fumagillin was eventually reported (Halasz et al., 2000).Preparation of the 1-oxospiro[2.5]heptanesystem by reaction of dimethylsulfoxonium methylide with substituted cyclohexanones generally proceeds with the formation of the exocyclic epoxide in which the oxygen atom has an axial orientation (Corey & Chaykovsky, 1965;Carlson & Behn, 1967).In connection with our studies on estrogen receptor beta-selective agonists (Hanson et al., 2018;Wetzel et al., 2022), we had the opportunity to prepare the title compound, C 19 H 30 O 2 Si, and we now present its synthesis and crystal structure.
The title compound (Fig. 1) has an extended conformation with a transoid t-Bu-Si-O-Ar moiety.The cyclohexane ring has a chair conformation with the aryl substituent in an equatorial position and the epoxide oxygen atom in a pseudoaxial orientation.The C7-O1-Si1-C3 torsion angle is À 177.40 ( 14) � .In the crystal, a weak C-H� � �O link (Fig. 2, Table 1) connects the molecules into inversion dimers featuring R 2 2 (8) loops.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2.

Figure 2
Unit-cell packing of the title compound.

Special details
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.

Figure 1
Figure 1The molecular structure of the title compound showing 50% displacement ellipsoids.
Symmetry code:

Table 2
Experimental details.