From Anilines to Aryl Ethers: A Facile, Efficient, and Versatile Synthetic Method Employing Mild Conditions

Abstract

We have developed a simple and direct method for the synthesis of aryl ethers by reacting alcohols/phenols (ROH) with aryl ammonium salts (ArNMe ), which are readily prepared from anilines (ArNR' , R'=H or Me). This reaction proceeds smoothly and rapidly (within a few hours) at room temperature in the presence of a commercially available base, such as KO Bu or KHMDS, and has a broad substrate scope with respect to both ROH and ArNR' . It is scalable and compatible with a wide range of functional groups.

Photoinduced C(sp3)−N Bond Cleavage Leading to the Stereoselective Syntheses of Alkenes

“…[6b] Since 2017, several groupsh ave furthere xtended the utility of pyridinium salts [15,16] from SE-acceptort oa lkyl radical source, by employinge ither transition-metal catalysis [17] or photochemicalp rocesses. [18] These impressive achievements indicate that the alkyl radical generation protocol by CÀNc leavage can open up conceptually new synthetic routes.A st he latest development in our work on CÀNb ondc leavage protocols, [13] we herein reporto ur results on C(sp 3 )ÀNb ond-cleavage-type MÀH reactions with alkyl Katritzkys alts by ap hotoredoxc atalytic process, affording alkyl-substituted alkenesw ith high yields and selectivity (Scheme 1). [19] Our basic concept was as follows.…”

“…On the other hand, cross-couplingp rotocols with amines/ anilines and their derivatives, [9,10] especially ammonium salts [11] as halide analogues, have also been well developed recently. [12][13][14] Amine groups occuri nm any biologically essential compounds and are widely used in industry for the preparation of pharmaceuticals and functional materials. The high stabilityo f aminoC ÀNb onds makes them very resistantt oc leavage reactions.…”

“…[9] Ammonium salts can be easily prepared from various amines/anilines, and such CÀNb onds exhibit higherr eactivity. However, whilea ryl ammoniums have provedh ighly reactive with transition-metal catalysts, [12,13] most alkyl ammoniumsa re quite inert with low-valence metal catalysts, [14] because alkyl CÀNs peciesa re weak acceptors for an electron pair or as ingle electron (SE) from transition metals. In contrast, owing to the low-lyinga romatic p*-orbital, pyridinium salts are excellent electron acceptors.…”

Direct Carboxylation of Electron‐Rich Heteroarenes Promoted by LiO‐tBu with CsF and [18]Crown‐6

“…The effectso fa dditives were examined, and to our delight, the reactivity of the base was largely enhanced upon the addition of CsF and [18]crown-6t oa fford 2a-H in ag ood yield of 86 %( entries 2-5). [23] Use of CsCl and CsI instead of CsF significantlyd ecreased the yield of 2a-H,w hereas that of [15]crown-5 instead of [18]crown-6 resulted in as lightd ecrease of the yield (entries6-8). Decreasing the amountso ft he reactants to two equivalents afforded a lower yield of 2a-H (entry 9).…”

“…As expected, the carboxylated products 2a and 2f were obtained in 99 and 92 %y ields, respectively (Scheme 2). [34] Ap lausible mechanism underlying this reaction is shown in Scheme1.H eteroarene is initially deprotonated by the base, [tBuOCO 2 M] or tBuOM, to form anionic species A,w hich then reacts with CO 2 to provide carboxylate B.E xchange of the cation from Li + to Cs + [23] as well as complexationo fC s + and [18]crown-6 [35] were consideredt oe nhance the reactivity of [tBuOCO 2 M] or tBuOM compared with that of their lithium counterparts.…”