Nickel precatalysts are potentially a more sustainable alternative to traditional palladium for the Suzuki–Miyaura coupling reaction. Currently, there is significant interest in reactions involving readily accessible phenolic derivatives such as aryl sulfamates, sulfamate moiety can act directing group prefunctionalization of aromatic backbone electrophile prior cross-coupling. By evaluating complexes Ni(0), (I), and (II) oxidation states we report precatalyst, (dppf)Ni(o-tolyl)(Cl) (dppf =...

Abstract Ni‐based precatalysts for the Suzuki–Miyaura reaction have potential chemical and economic advantages compared to commonly used Pd systems. Here, we compare Ni supported by dppf ligand in 3 oxidation states, 0, I II. Surprisingly, at 80 °C they give similar catalytic activity, with all systems generating significant amounts of during reaction. At room temperature a readily accessible bench‐stable II precatalyst is highly active can couple synthetically important heterocyclic...

A number of new transition metal catalyzed methods for the formation C(sp2 )-C(sp3 ) bonds have recently been described. These reactions often utilize bidentate polypyridyl-ligated Ni catalysts, and paramagnetic NiI halide or aryl species are proposed in catalytic cycles. However, there is little knowledge about complexes this type. Here, we report synthesis through elementary cycles bond formation. We investigate ability these to undergo organometallic that relevant coupling stoichiometric...

Esters are valuable electrophiles for cross-coupling due to their ubiquity and ease of synthesis. However, harsh conditions traditionally required the effective ester substrates. Utilizing a recently discovered precatalyst, Pd-catalyzed Suzuki-Miyaura Buchwald-Hartwig reactions involving cleavage C(acyl)-O bond aryl esters that proceed under mild reported. The Pd(II) precatalyst is highly active because it reduced Pd(0) species more rapidly than previous precatalysts.

In this work, Ni(I) aryl species that are directly relevant to cross-coupling have been synthesized. Transmetalation of (dppf)NiIX (dppf = 1,1′-bis(diphenylphosphino)-ferrocene, X Cl, Br) with Grignard reagents or boronic acids in the presence base produces form (dppf)NiI(Ar) (Ar Ph, o-tolyl, 2,6-xylyl, 2,4,6-mesityl, 2,4,6-iPr3C6H2). The stability is inversely correlated steric bulk on ligand. most unstable active precatalysts for Suzuki–Miyaura reactions because they rapidly decompose...

Structural characterization of lignin extracted from the bio-oil produced by fast pyrolysis switchgrass (Panicum virgatum) is reported. This important for understanding utility as a chemical feedstock in pyrolysis-based biorefinery scheme. Pyrolysis induces variety structural changes to addition reduction molecular weight. The guaiacol units remain largely intact, and some hemicellulose stays covalently linked lignin. However, two-dimensional 1H–13C HSQC NMR analysis shows an absence...

There is currently significant interest in the development of efficient nickel precatalysts for cross-coupling. In this work, 14 nickel(II) form (dppf)Ni(aryl)(X) (dppf = 1,1′-bis(diphenylphosphino)ferrocene, X Cl, Br) were synthesized. particular, both electronic and steric properties aryl group modified to understand how affects precatalyst activation. Using EPR spectroscopy, it was demonstrated that amount off-cycle nickel(I) species which are formed via comproportionation during...

Using a recently discovered precatalyst, the first Pd-catalyzed Suzuki–Miyaura reactions using aryl sulfamates that occur at room temperature are reported. In complementary work, it is demonstrated related precatalyst can facilitate coupling of silanolates, which less toxic and reactive nucleophiles than boronic acids with chlorides. By combining our results modern electrophiles nucleophiles, Hiyama–Denmark

Aryl carbonates, a common protecting group in synthetic organic chemistry, are potentially valuable electrophiles cross-coupling reactions. Here, after performing thorough evaluation of different precatalysts, we demonstrate that (dcypf)Ni(2-ethylphenyl)(Br) (dcypf = 1,1-bis(dicyclohexylphosphino)ferrocene) is an efficient precatalyst for Suzuki–Miyaura reactions using variety aryl carbonates as substrates. Mechanistic studies indicate (dcypf)Ni(2-ethylphenyl)(Br), which contains bidentate...

Aryl-substituted pyridine(diimine) iron complexes promote the catalytic [2 + 2] cycloadditions of alkenes and dienes to form vinylcyclobutanes as well oligomerization butadiene generate divinyl(oligocyclobutane), a microstructure poly(butadiene) that is chemically recyclable. A systematic study on series their ruthenium congeners has provided insights into essential features catalyst promotes these cycloaddition reactions. Structural computational studies identified structural rigidity...

Abstract Ni‐based precatalysts for the Suzuki–Miyaura reaction have potential chemical and economic advantages compared to commonly used Pd systems. Here, we compare Ni supported by dppf ligand in 3 oxidation states, 0, I II. Surprisingly, at 80 °C they give similar catalytic activity, with all systems generating significant amounts of during reaction. At room temperature a readily accessible bench‐stable II precatalyst is highly active can couple synthetically important heterocyclic...

Abstract A number of new transition metal catalyzed methods for the formation C(sp 2 )–C(sp 3 ) bonds have recently been described. These reactions often utilize bidentate polypyridyl‐ligated Ni catalysts, and paramagnetic I halide or aryl species are proposed in catalytic cycles. However, there is little knowledge about complexes this type. Here, we report synthesis through elementary cycles bond formation. We investigate ability these to undergo organometallic that relevant coupling...

While hydroxy-terminated polybutadiene (HTPB) has been traditionally employed as a binder prepolymer for solid rocket booster applications, the hydrocarbon main chain is energetically inert and contributes little to overall energy content of formulation. Here, (1,n′-divinyl)oligocyclobutane (DVOCB), structural isomer containing 1,3-enchained cyclobutanes in polymer backbone, investigated candidate. The synthetic modularity DVOCB also demonstrated through postsynthetic dihydroxylation...

A series of PtII and PtIV aminotroponimate (ATI = N-tolyl-aminotroponiminate) complexes has been prepared. The complex (ATI)Pt(CH3)(SMe2) (1a) is synthesized from the reaction [Li][ATI] with (Me)(Cl)Pt(SMe2)2. Addition either ethylene or carbon monoxide to 1a results in formation (ATI)Pt(CH3)(η2-C2H4) (1b) (ATI)Pt(CH3)(CO) (1c), respectively. Oxidative addition MeOTf MeI [(ATI)Pt(CH3)2(X)(SMe2)] (X OTf (3), I (2)). Complex 3 reacts isocyanides, which replace triflate ligand form...

Diene self-exchange reactions of the 17-electron, formally cobalt(0) cyclooctadienyl precatalyst, (R,R)-(iPrDuPhos)Co(COD) (P2CoCOD, (R,R)-iPrDuPhos = 1,2-bis((2R,5R)-2,5-diisopropylphospholano)benzene, COD 1,5-cyclooctadiene) were studied using natural abundance and deuterated 1,5-cyclooctadiene. Exchange free coordinated diene was observed at ambient temperature in benzene-d6 solution kinetic studies support a dissociative process. Both neutral P2CoCOD 16-electron, cationic cobalt(I)...

Closed-loop recycling offers the opportunity to help mitigate plastic waste through reversible polymer construction and deconstruction. While examples of chemical polymers are known, few have been applied materials derived from abundant commodity olefinic monomers that building blocks ubiquitous resins. Here we describe a [2+2] cycloaddition oligomerization 1,3-butadiene yield previously unrealized telechelic microstructure (1,n’-divinyl)oligocyclobutane. This material is thermally stable,...