Chalcone epoxide intermediates in the syntheses of lignin-related phenylcoumarans.
Compounds (2R*,3S*)-1-(3,4-dimethoxyphenyl)-3-{3-methoxy-2-[(2R*)-tetrahydropyran-2-yloxy]phenyl}-2,3-epoxy-1-propanone, C23H26O7, (I), and trans-1-(3,4-dimethoxyphenyl)-3-[3-methoxy-2-(methoxymethoxy)phenyl]-2,3-epoxy-1-propanone, C20H22O7, (II), were obtained on epoxidation of chalcones. The stereochemistries of (I) and (II) were elucidated. In both compounds, the substituents on the oxirane ring are trans-oriented. Compound (I) was obtained together with a diastereometric form that differs from (I) with respect to the configuration of the asymmetric C atom in the tetrahydropyran group. The geometries of the substituted oxirane rings of (I) and (II) are very similar. The hydrogen-bonding patterns, mediated via weak C-H...O interactions, differ considerably. The crystal structures of (I) and (II) are compared with those of related chalcone epoxides. The conversion of (I) and (II) into lignin-related phenylcoumarans is discussed.
Langer
Vratislav
V
Environmental Inorganic Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-41296 Göteborg, Sweden. langer@chalmers.se
Li
Shiming
S
Lundquist
Knut
K
D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry*; D047188:Chalcones / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008031:Lignin / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure
D001572:Benzofurans; D047188:Chalcones; C028770:chalcone epoxide; D008031:Lignin; C043168:coumaran