Selective Hydroarylation of 1,3‐Diynes Using a Dimeric Manganese Catalyst: Modular Synthesis of Z‐Enynes

Abstract

The transition-metal-catalyzed selective hydroarylation of unsymmetrical alkynes represents the state-of-art in organic chemistry, and still mainly relies on the use of precious late-transition-metal catalysts. Reported herein is an unprecedented Mn -catalyzed hydroarylation of unsymmetrical 1,3-diyne alcohols with commercially available arylboronic acids with predictive selectivity. This method addresses the challenges in regio-, stereo-, and chemoselectivity. It offers a general, convenient and practical strategy for the modular synthesis of multisubstituted Z-configurated conjugated enynes. This protocol is distinguished by its operational simplicity, complete selectivity, excellent functional-group compatibility, and gram-scale potential. A dimeric Mn species, Mn (CO) Br , was proven to be a much more efficient catalyst precursor than Mn(CO) Br.

Three‐Dimensional Carbon Framework Anchored Polyoxometalate as a High‐Performance Anode for Lithium‐Ion Batteries

“…X‐ray photoelectron spectroscopy (XPS) of the Carbon‐PMo 12 showed that the composite was composed of C, N, O, P, and Mo elements (Figure S3, Supporting Information). Notably, the N 1s peak of the Carbon‐PMo 12 composite (Figure e) can be divided into three peaks at 402.7, 400.8, and 398.5 eV, which correspond to graphitic‐N, pyrrolic‐N, and pyridinic‐N species, respectively . The C 1s peaks of the Carbon‐PMo 12 located at 289.1, 285.8, and 284.8 eV (Figure S3) were characteristic of C−N, C=N, and C−C/C=C, respectively .…”

Dimeric Manganese‐Catalyzed Hydroarylation and Hydroalkenylation of Unsaturated Amides

“…In 2018, the first example of selective hydroarylation of 1,3‐diynes with arylboronic acids enabled by a dimeric Mn(I)‐catalyzed was reported by our laboratory . However, the major challenges for Mn‐catalyzed selective hydroarylation of alkenes stem from largely undeveloped elementary units, such as transmetallation and migratory insertion compared with Pd or Rh catalysts, which have already gained great momentum in transition metal‐catalyzed conjugate addition of organometallics to electron‐deficient alkenes (Scheme a) .…”

“…(3)–(5)]. Although it is currently premature to describe a clear mechanistic understanding of Mn(I)‐catalyzed hydroarylation and hydroalkenylation of α,β‐unsaturated amides, we propose a plausible mechanism in Scheme b. Owing to the weak coordination ability of bromide, the dimeric manganese catalyst could become two reactive 16‐electron manganese species ( 8 ) at 120 °C, and these will immediately undergo transmetallation with aryl boronic acids in the presence of external base to generate an intermediate ( 9 ) . As the use of different inorganic bases can influence the reaction efficiency, we speculated the Mn‐mediated transmetallation chemistry with arylboronic acids might be similar to palladium .…”

Manganese‐Catalyzed Hydroarylation of Unactivated Alkenes

“…The reaction starts with the formation of ArMn(CO) 5 from MnBr(CO) 5 and arylboronic acid 2 with the assistance of base through a transmetalation process. [10] The release of CO ligands and coordination of alkene 1 with ArMn(CO) 5 delivers the manganacycle Mn-II. Migratory insertion of the olefin moiety into the CÀMn bond in Mn-II gives the manganacycle Mn-I.…”

“…Manganese, as an earth-abundant transition metal, is a potential candidate for new catalyst development in sustainable chemistry. [8] So far, manganese-catalyzed hydroarylation of alkynes via arylmanganese intermediates resulted from either C À H activation of arenes [9] or transmetalation of arylboronic acids [10] has been well developed since 2013. Additionally, manganese-catalyzed hydroarylation of activated alkenes has been reported since 2014.…”