title: Photochemical hydroxylation of 1-methyl-9,10-anthraquinones: synthesis of 9'-hydroxyaloesaponarin II.
abstract: Photolysis of 1-methyl-9,10-anthraquinones in the presence of oxygen yields endoperoxides that can be reduced to produce 1-hydroxymethyl-9,10-anthraquinones. The reaction proceeds in a fashion similar to that of other o-alkylphenones which yield either a 1,4-diradical or a "photoenol" upon irradiation. Anthraquinones undergo photochemistry at a wavelength where the endoperoxide is transparent, allowing its isolation. A singlet oxygen quencher had no effect on the rate of formation of the endoperoxide. The photochemical hydroxylation has been used in a total synthesis of a naturally occurring polyketide, 9'-hydroxyaloesaponarin II.
authors.affiliation: Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27106, USA.
authors.forename: Salwa
authors.initials: S
authors.lastname: Elkazaz
authors.forename: Paul B
authors.initials: PB
authors.lastname: Jones