Copper(II)‐Catalyzed Monoarylation of Vicinal Diols with Diaryliodonium Salts

Abstract

Selective and efficient: The copper(II)‐catalyzed selective monoarylation of vicinal diols with diaryliodonium triflates was successfully developed. In this catalytic process high chemoselectivity was achieved, even in the presence of a 1:1 mixture of the 1,2‐diol and the mono‐ol, and a wide range of substrates was tolerated, giving the monoarylated products in good to excellent yields (see scheme).

Metal-Free Synthesis of Aryl Ethers in Water

“…The yield of 2a increased to 64% with 2 equivalents of base (entries 10-11), and the reaction could be performed at 50 °C for 3 h instead (entry 12). One hour reaction time was sufficient, and potassium or lithium hydroxide gave similar results (entries [13][14][15][16].…”

“…A recent copper-catalyzed monoarylation of vicinal diols with diaryliodonium salts was inefficient for regular alcohols. 13 The lack of a general, metal-free arylation methodology for aliphatic alcohols under mild and environmentally benign conditions prompted us to develop an arylation reaction with diaryliodonium salts, which are stable hypervalent iodine reagents of low toxicity. 14, 15 Herein our preliminary results are disclosed.…”

Synthesis of Functionalized Dihydrobenzofurans by Direct Aryl C−O Bond Formation under Mild Conditions

“…[9] According to our reaction design, a mild Cu-catalyzed intramolecular C—H arylation of alcohols [10] affording dihydrobenzofurans will be accomplished via the intermediacy of non-symmetric diaryliodonium salts, which were to be prepared in situ and processed further without isolation. The choice of the prototypical substrate, 2-(3-methoxyphenyl)-2-cyclohexen-1-ol ( 1 , Table 1) was influenced by its relevance to eventual synthesis targets (galantamine, morphine).…”

“…[9] Indeed, addition of 1.0 equiv Cu(OTf) 2 to the preformed diaryl-λ 3 -iodane (PIFA, TFE, 0 °C, 25 min) afforded 3 exclusively in 52% yield (Table 1, entry 3). To suppress alkene isomerization in the initially formed benzofuran 2 , presumably acid-mediated, another 4 equiv of Et 3 N were added prior to the addition of copper catalyst, which delivered 2 in 62% yield (entry 4).…”

Synthesis of Functionalized Dihydrobenzofurans by Direct Aryl C−O Bond Formation under Mild Conditions

“…[9] According to our reaction design, am ild Cu-catalyzed intramolecular CÀH arylation of alcohols [10] affording dihydrobenzofurans will be accomplished via the intermediacyo fn on-symmetric diaryliodonium salts,w hich were to be prepared in situ and processed further without isolation. [9] According to our reaction design, am ild Cu-catalyzed intramolecular CÀH arylation of alcohols [10] affording dihydrobenzofurans will be accomplished via the intermediacyo fn on-symmetric diaryliodonium salts,w hich were to be prepared in situ and processed further without isolation.…”