196944-33-9Relevant academic research and scientific papers
Novel ipso-Substitution of p-Sulfinylphenols through the Pummerer-Type Reaction: A Selective and Efficient Synthesis of p-Quinones and Protected p-Dihydroquinones
Akai, Shuji,Takeda, Yoshifumi,Iio, Kiyosei,Takahashi, Kenji,Fukuda, Nobuhisa,Kita, Yasuyuki
, p. 5526 - 5536 (2007/10/03)
The treatment of p-sulfmylphenols 3a-q with trifluoroacetic anhydride caused a Pummerer-type reaction on aromatic rings and concomitant desulfurization to give mixtures of the corresponding p-dihydroquinones 9 and p-quinones 10, which were subsequently oxidized under mild conditions to provide high yields of p-quinones 10. On the other hand, the treatment of p-(phenylsulfinyl)-phenyl ethers 6 with trifluoroacetic anhydride in the presence of styrene caused the direct ipso-substitution of the sulfinyl groups into trifluoroacetoxy groups, giving the protected dihydroquinones 14 in high yields. Both types of reactions were generally completed below room temperature within 1 h and compatible with various functional groups such as the allyl, carbonyl, ester, amide, and silyloxy groups. The preparation of the p-sulfmylphenols 3 and the silyl ethers 6 is also described through p-specific thiocyanation of phenols followed by the Grignard reaction and oxidation.
