Regiospecific Photochemical Synthesis of Methylchrysenes
Bøhme, Thomas Andre; Egeland, Mari; Lorentzen, Marianne; Mady, Mohamed Fawzy Hamed Attia; Solbakk, Michelle F.; Sæbø, Krister Samsonsen; Jørgensen, Kåre Bredeli
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2022-12Metadata
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Böhme, T., Egeland, M., Lorentzen, M., Mady, M. F., Solbakk, M. F., Sæbø, K. S., & Jørgensen, K. B. (2022). Regiospecific Photochemical Synthesis of Methylchrysenes. Molecules, 28(1), 237 10.3390/molecules28010237Abstract
Methylated polycyclic aromatic hydrocarbons (PAHs) are suspected to be some of the toxic compounds in crude oil towards marine life and are needed as single compounds for environmental studies. 1-, 3- and 6-methylchrysene (3a,b,c) were prepared as single isomers by photochemical cyclization of the corresponding stilbenoids in the Mallory reaction using stoichiometric amounts of iodine in 82-88% yield. 2-methylchrysene (3d) was prepared by photochemical cyclization where the regioselectivity was controlled by elimination of an ortho-methoxy group under acidic oxygen free conditions in 72% yield. These conditions failed to form 4-methylchrysene from the corresponding stilbenoid. All stilbenoids were made from a common naphthyl Wittig salt and suitably substituted benzaldehydes. We have also demonstrated that methylchrysenes can be oxidized to the corresponding chrysenecarboxylic acids by KMnO4 in modest yields.