Crystal structure of 2-isopropyl-4-methoxy-5-methylphenyl 4-methylbenzenesulfonate

Abstract

The title compound, C 18 H 22 O 4 S, an hemisynthetic product, was obtained by the tosylation reaction of the naturally occurring meroterpene p-methoxythymol. The molecule comprises a tetrasubstitued phenyl ring linked to a toluenesulfonate through one of its O atoms. In the crystal, C-HÁ Á ÁO and C-HÁ Á Á interactions link the molecules, forming a three-dimensional network. Chemical contextTosylation of alcohols is an important transformation in organic synthesis. This transformation is usually achieved with p-toluene sulfonyl chloride, which is very reactive (Greene & Wuts, 1999;Yoshida et al., 1999). Tosylate is an important functional group in organic synthesis as it makes a good leaving group (Wagner & Zokk, 1955;Sandler & Karo, 1983). Indeed, tosylates are used as intermediates in the synthesis of several drugs (Kim et al., 1995;Morgan et al., 1997). Furthermore, they have also been found to possess important biological activities (Kacem et al., 2002;Kaleemullah et al., 2012).The hemisynthesis of 2-isopropyl-4-methoxy-5-methylphenyl 4-methylbenzenesulfonate 2 from naturally occurring p-methoxythymol 1 was undertaken with the aim of preparing meroterpenic tosylate. X-ray single-crystal structure analysis allowed its full structure to be confirmed unambiguously. Structural commentaryCompound 2 is built up from a tetrasubstituted phenyl ring linked to a toluenesulfonate unit through one of its oxygen atoms (Fig. 1). The two phenyl rings form a dihedral angle of 60.03 (9) . Atoms S1 and C5 0 are coplanar with the C1 0 -C6 0 phenyl ring, their distances from the plane being 0.057 (3) and 0.031 (3) Å , respectively. Considering the connected atoms of ISSN 2056-9890 the four substituents on the C1-C6 phenyl ring, three of them O2, C8 and C11 are roughly in the plane of the phenyl ring, deviating by only 0.011 (3), 0.014 (3) and 0.012 (3) Å , respectively, from the mean plane, whereas atom O1 is displaced slightly out of the plane by 0.101 (3) Å . This slight distortion might be related to the occurrence of a weak C-HÁ Á Á interaction between the C9 atom and the centroid Cg2 of the C1 0 -C6 0 phenyl ring (Table 1). Supramolecular featuresIn the crystal, pairs of molecules are linked though C-HÁ Á ÁO interactions (Table 1), forming pseudo-dimer arranged around inversion centers (Fig. 2). Further C-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions (Table 1, Fig. 2) lead to the formation of a three-dimensional network. Database surveyA search of the Cambridge Structural Database (CSD, version 5.38, last update May 2017; Groom et al., 2016) for a tosylate fragment bearing an organic substituent on one of its oxygen atoms revealed only three hits. Two of these compounds are closely related to compound 2. The first, 5-bromo-2,3-dimethylphenol-1-(4-methylphenylsulfonyloxy)benzene (KAWDAN; Niestroj et al., 1998), is built up from a tosylate attached to a phenyl ring substituted by two methyl groups and one bromine atom whereas the second, tetramethyl-pphenylene p-ditoluenesulfonate (TMPDTS; Wieczorek et al., 1975), is b...