- Styryl and functionalized aryl derivatives of lawsone through metal-free cross-coupling of its BF3-activated phenyliodonium ylide with cinnamaldehydes and arylaldehydes
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Phenyliodonium ylide of lawsone activated with BF3?Et2O reacts with cinnamaldehydes to afford 2-hydroxy-3-styryl-1,4-naphthoquinones in good to excellent yields and relatively high level of stereospecificity through deformylation of the aldehydes. The product yield is diminished with a methoxy substituted cinnamaldehyde and becomes zero with a dimethoxy substituted substrate giving rise to another product, 2-hydroxy-3-aryl-1,4-naphthoquinone. The reaction of the same ylide with salicylic aldehydes forms 2-hydroxy-3-(2-hydroxyaryl)-1,4-naphthoquinones and/or benzo[d]naphtha[2,1-b]furano-5,6-diones, depending on the reaction conditions applied. Plausible reaction mechanisms explaining the formation of these products are proposed. The products showed potent antioxidant activity and inhibited lipoxygenase.
- Malamidou-Xenikaki, Elizabeth,Tsanakopoulou, Maria,Chatzistefanou, Maria,Hadjipavlou-Litina, Dimitra
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p. 5650 - 5661
(2015/08/03)
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- Arylation of lawsone through BF3-mediated coupling of its phenyliodonium ylide with activated arenes and aromatic aldehydes
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Phenyliodonium ylide of lawsone, activated by BF3·Et 2O, reacts with electron-rich arenes to afford the corresponding 2-aryl-3-hydroxy-1,4-naphthoquinones, in a coupling reaction without metal catalysts. The same type of products, in greater variety and higher yields, are obtained from the reaction of the BF3·Et2O- activated ylide with aromatic aldehydes in a synthetically and mechanistically interesting deformylation reaction.
- Glinis, Elias,Malamidou-Xenikaki, Elizabeth,Skouros, Haris,Spyroudis, Spyros,Tsanakopoulou, Maria
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experimental part
p. 5786 - 5792
(2010/09/09)
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