The direct oxidative coupling reaction has been an attractive tool for environmentally benign chemistry.Reported herein is that the hypervalent iodine catalyzed oxidative metalfree cross-coupling reaction of phenols can be achieved using Oxone as at erminal oxidant in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP). This method features ah igh efficiency and regioselectivity,a sw ell as functional-group tolerance under very mild reaction conditions without using metal catalysts.

The direct oxidative coupling reaction has been an attractive tool for environmentally benign chemistry.Reported herein is that the hypervalent iodine catalyzed oxidative metalfree cross-coupling reaction of phenols can be achieved using Oxone as at erminal oxidant in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP). This method features ah igh efficiency and regioselectivity,a sw ell as functional-group tolerance under very mild reaction conditions without using metal catalysts.The biaryl unit including phenol is an important structural motif for aw ide range of functional molecules such as bioactive natural products,l iquid crystals,a nd ligands for transition-metal catalysts.[1] Thec ommon approaches to the syntheses of these structures involve cross-couplings between aryl halides and organometallic reagents.[2] In these cases of multistep syntheses,s uch as Suzuki or Stille coupling,t he phenol moiety usually has to be protected. Recently,t ransition-metal-catalyzed direct functionalization of the CÀH bonds on aromatic compounds,involving the activation of the aromatic C À Hbond, has attracted much attention in terms of synthetic efficiencya nd minimization of atomic waste. [3,4] In contrast, the oxidative cross-coupling of unprotected phenols has received considerable attention because of the atom-economical and environmentally friendly processes. [5] Although various kinds of homocoupling reactions of unprotected phenols involving the use of Fe,C u, Mn, and Ti salts have been developed, [6] thecatalytic oxidative cross-coupling reaction of phenols by CÀH/CÀH' coupling has remained challenging. [7] This reaction is ac hallenge because,w hen simple phenols are employed in oxidative cross-couplings,the desired products are often concomitantly formed along with homocoupling by-products.M oreover,t he formation of higher-molecular-weight polymers or C,O-connected phenol portions,for example,quinol ethers,might also occur depending on the oxidant and the reaction conditions.[2b] Am ajor reason for this side reaction is the difficulty associated with the tunable reactivity of phenols by controlling their oxidation potential using aprotecting group for the phenol hydroxy group.T herefore,t he development of an efficient catalytic cross-coupling of unprotected phenols for the construction of biaryl compounds is still highly desirable.R ecently,W aldvogel and co-workers reported an electrochemical phenolarene cross-coupling reaction using boron-doped diamond electrodes.[8] Very recently,the iron-catalyzed oxidative crosscoupling reaction of phenols with arenes was successfully achieved.[9] While recent metal-catalyzed cross-couplings of phenols have been studied, the organocatalytic cross-coupling reaction still remains particularly challenging.R ecently,w e developed the oxidative cross-coupling reaction of aromatic compounds using hypervalent iodine reagents. [10][11][12][13][14][15] Inspired by these studies,wenow report abroadly applicable organoiodine(III)-catalyzed oxidative cross-coupling reaction of pheno...

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A hypervalent iodine(III)‐catalyzed intermolecular oxidative cross‐coupling reaction of electron‐rich aromatic compounds is achieved by using a catalytic amount of an iodoarene and an inorganic oxidant.

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