Direct Carbohydroxylation of Arylalkenes with Allylic Alcohols: Cooperative Catalysis of Copper, Silver, and a Brønsted Acid

Abstract

The cooperative catalysis of copper,s ilver,a nd Brønsted acid is presented as an ew strategy for olefin functionalization. The catalytic direct carbohydroxylation of arylalkenes with allylic alcohols provided as traightforward and efficient approach for preparing 4,5-unsaturated alcohols. Synthetically useful functional groups,such as Cl, Br,carbonyl, and chloromethyl, remained intact during the functionalization reaction.The transition metal catalyzed functionalization of olefins is ap owerful tool to convert readily available petrochemical feedstocks into valuable synthetic building blocks. [1] The development of convenient and efficient methods for the functionalization of olefins is still ar esearch hotspot in organic synthesis although many catalytic methods for the mono-and di-functionalization of olefins have been reported over the past years.Many kind of metals,such as palladium, [2] rhodium, [3] gold, [4] nickel, [5] and copper, [6] were employed as the catalysts for this purpose.Direct carbohydroxylation of alkenes,w hich is the addition of C( alkyl and aryl) and OH to alkenes,i sa n important synthetic method for functionalization of the C=C bond. However,tothe best of our knowledge,only few papers on direct carbohydroxylation, namely arylhydroxylation of alkenes,h ave been reported, and they involve ar adical process. [7] Some examples of indirect carbohydroxylation of alkenes are known. [8] In addition, catalytic allylation of olefins,aH eck-type coupling reaction using allylic ethers, [9] allylic carbonates, [9] allylic tosylate, [10] and allylic alcohols [11] as allyl sources have also been reported. However,a sf ar as we know,t here is no precedent of direct addition of allylic alcohols to alkenes using transition-metal catalysts.H erein, we report that aw ide range of arylalkenes react with allylic alcohols under the cooperative catalysis of Cu, Ag, and[*] W. Ahmed, [+] Dr.

Ni-Catalyzed Regioselective 1,2-Dialkylation of Alkenes Enabled by the Formation of Two C(sp3)–C(sp3) Bonds

“…Alkene difunctionalization reactions are largely successful for terminal alkenes with C­(sp 2 )-hybridized coupling partners . Internal alkenes are less polarized and more sterically hindered than terminal alkenes and, therefore, present a fundamental challenge for reactivity . Moreover, coupling of secondary carbons with internal alkenes, which requires bond formation between two sterically demanding secondary C­(sp 3 ) hybridized carbons involving secondary C­(sp 3 )-alkylmetal intermediates, is even more challenging since the molecular assembly at the metal center becomes highly crowded and raises the activation barrier for the reaction.…”

Synergistic Dual Transition Metal Catalysis

“…Recently, Bao and co-workers reported direct carbohydroxylation of aryl alkenes 517 with allylic alcohol 518 , adding an olefin and a hydroxyl moiety across the double bond (Scheme ). This unprecedented transformation was realized through Cu/Ag synergistic catalysis, which to our knowledge is notably rare in the scientific literature. The reaction yields synthetically useful 4,5-unsaturated alcohol 519 in good yields.…”

Efficient and environmentally-friendly access to 4,5-unsaturated sulfonamides through ligand-free copper-BF3-catalyzed three-component alkene carbo-sulfonamidation

“…A plausible mechanism is proposed (Scheme 6) on the basis of the results of the control experiments and the literature. 53–55 The Lewis acid (BF 3 ·ether) first reacts with the basic sulfonamide (NH 2 SO 2 Me) to generate a Lewis acid-sulfonamide pair that further reacts with Cu( i ) to give the copper-Lewis acid-sulfonamide complex ( A ). This key intermediate A coordinates with the cinnamyl cation generated from the dehydration of cinnamyl alcohol, forming the π-allyl-copper intermediate B .…”

“…A plausible mechanism is proposed (Scheme 6) on the basis of the results of the control experiments and the literature. [53][54][55] The Lewis acid (BF 3 •ether) first reacts with the basic sulfonamide (NH 2 SO 2 Me) to generate a Lewis acid-sulfonamide pair that further reacts with Cu(I) to give the copper-Scheme 4 Gram-scale synthesis of 4ad. Lewis acid-sulfonamide complex (A).…”