Synthese von Naturstoffen mit Alkyl‐methoxy‐1,4‐benzochinon‐Struktur

Abstract

Synthesis of Natural Compounds with Alkyl‐methoxy‐1,4‐benzoquinone StructureThe 1,4‐benzoquinones 1–7 occurring in various plants and having interesting biological properties have been synthesized from the tetrahydropyranyl ethers 17 and 21. Reaction with n‐butyllithium gave selectively the ortho‐lithiated compounds. These could be alkylated with the haloalkenes 13–16 and haloalkanes to give the substituted phenols 18–20 and 22–25 in high yield after methanolysis. Alkylations of the methoxyisopropylether 8 of 10‐undecyn‐1‐ol with bromobutane and bromohexane gave 9 and 10. These alkynols could be selectively hydrogenated with Lindlar‐Palladium catalyst to give the (Z)‐alkenols 11 and 12 which could be converted into the bromoalkenes 13, 14 and the iodoalkenes 15, 16. Oxidation of the phenols 18–20 and 22–25 with molecular oxygen in the presence of salcomine as catalyst produced the substituted 1,4‐benzoquinones 1–3 and 26–29 in high yield. Selective hydrolysis with perchloric acid converted 26–29 into the natural products 4–7.