Introduction of a Hydroxy Group at the Para Position and N-Iodophenylation of N-Arylamides Using Phenyliodine(III) Bis(Trifluoroacetate)

Abstract

The reaction of anilides with phenyliodine(III) bis(trifluoroacetate) (PIFA) in trifluoroacetic acid (TFA), TFA-CHCl3, or hexafluoroisopropyl alcohol (HFIP) is described. When the acyl group of the anilide is highly electronegative, such as trifluoroacetyl, or the phenyl group is substituted with an electron-withdrawing group, the 4-iodophenyl group is transferred from PIFA to the amide nitrogen to afford acetyldiarylamines. On the other hand, when the acyl group contains an electron-donating function, such as 4-methoxyphenyl, or the phenyl group is substituted with an electron-donating group, a trifluoroacetoxy group is transferred to the para position of the anilide aromatic ring. This group is hydrolyzed during workup to produce the corresponding phenol.

Hydrohalogenation of N-acetyl(aroyl)-1,4-benzoquinone monoimines

“…The characteristics of aminophenols Ia-If are in agreement with the published data: Ia, mp 168-169°C (169°C [33]); Ib, mp 223-225°C (226-230°C [34,35] N-Acetyl(aroyl)-1,4-benzoquinone monoimines IIa-IIf, VIIIa-VIIIf, Xa-Xf, XXIa-XXIc. a.…”

Chemistry of Polyvalent Iodine

“…The introduction of hydroxy, alkoxy and acetoxy groups to the activated aromatic ring using [bis(acyloxy)iodo]arenes as oxidants has also been reported. N -Arylamides can be hydroxylated in the para position by BTI in trifluoroacetic acid at room temperature 337. The oxidation of 2,5-dihydroxyacetophenone with DIB in different alcohols leads to a regioselective alkoxylation, providing a convenient route for the synthesis of 6-alkoxy-2,5-dihydroxyacetophenones 338.…”

Phenyliodine Bis(trifluoroacetate) Mediated Intramolecular Oxidative Coupling of Electron-Rich N-Phenyl Benzamides

“…Compound 1k and 1l were transformed smoothly to 2k and 2l too in good yields ( Table 2, entries 10 and 11). However, the expected reaction failed to take place for compounds 1m-p ( Table 2, entries [11][12][13][14].…”

“…It is well-known that acids can promote the hypervalent iodine reagent mediated electron transfer process as well as the geneation of intermediates like B. 2,3,14 As a result, the formation of benzoxazoles was facilitated by BF 3 ·OEt 2 or TMSOTf according to the mechanisms shown in Scheme 3.…”