Novel ipso-Substitution of p-Sulfinylphenols through the Pummerer-Type Reaction: A Selective and Efficient Synthesis of p-Quinones and Protected p-Dihydroquinones
摘要:
The treatment of p-sulfinylphenols 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-sulfinylphenols 3 and the silyl ethers 6 is also described through p-specific thiocyanation of phenols followed by the Grignard reaction and oxidation.
Novel ipso-Substitution of p-Sulfinylphenols through the Pummerer-Type Reaction: A Selective and Efficient Synthesis of p-Quinones and Protected p-Dihydroquinones
摘要:
The treatment of p-sulfinylphenols 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-sulfinylphenols 3 and the silyl ethers 6 is also described through p-specific thiocyanation of phenols followed by the Grignard reaction and oxidation.
Facile and Efficient Sulfenylation Method Using Quinone Mono-<i>O,S</i>-Acetals under Mild Conditions
作者:Masato Matsugi、Kenji Murata、Kentoku Gotanda、Hisanori Nambu、Gopinathan Anilkumar、Keita Matsumoto、Yasuyuki Kita
DOI:10.1021/jo001710q
日期:2001.4.1
A novel sulfenylation method induced by aromatization of quinone mono-O,S-acetals is described. These sulfenylation reagents readily react with silyl enolethers or electron rich aromatic compounds to give sulfenylation products under mild conditions. In particular, O,S-acetal 2j, which possesses a pentafluorophenylthio function, is the most effective reagent from the standpoint of the adaptability for various substrates.
An efficient sulfenylation of aromatics using highly active quinone mono O , S -acetal bearing a pentafluorophenylthio group
作者:Masato Matsugi、Kenji Murata、Hisanori Nambu、Yasuyuki Kita
DOI:10.1016/s0040-4039(00)02186-9
日期:2001.2
A facile sulfenylation of various aromatic nuclei was achieved by use of the novel sulfenylation reagent, the quinone mono O,S-acetal bearing a pentafluorophenylthio group. This reagent functions below 0 degreesC in the presence of a catalytic amount of TMSOTf. (C) 2001 Elsevier Science Ltd. All rights reserved.