Alkynes Between Main Group Elements: From Dumbbells via Rods to Squares and Tubes

Gleiter, Rolf; Werz, Daniel B.

doi:10.1021/cr9003727

Cited by 83 publications

(37 citation statements)

References 416 publications

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“…This is consistent with the literature where Bu t OCCOBu t is the only known stable bis (oxy)acetylene (49). All other derivatives react further at room temperature to give ill-defined mixtures of products (50), and Bu t OCCOBu t can be converted to a squarate derivative by thermolysis (51). This generates a ketene through isobutene elimination and hydrogen migration to give Bu t OCðHÞ ¼ C ¼ O that undergoes a [2 þ 2]-cycloaddition with the parent Bu t OCCOBu t (52).…”

Section: Resultssupporting

confidence: 92%

Homologation and functionalization of carbon monoxide by a recyclable uranium complex

Gardner

Stewart

Davis

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

163

110

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Carbon monoxide (CO) is in principle an excellent resource from which to produce industrial hydrocarbon feedstocks as alternatives to crude oil; however, CO has proven remarkably resistant to selective homologation, and the few complexes that can effect this transformation cannot be recycled because liberation of the homologated product destroys the complexes or they are substitutionally inert. Here, we show that under mild conditions a simple triamidoamine uranium(III) complex can reductively homologate CO and be recycled for reuse. Following treatment with organosilyl halides, bis(organosiloxy)acetylenes, which readily convert to furanones, are produced, and this was confirmed by the use of isotopically 13 C-labeled CO. The precursor to the triamido uranium(III) complex is formed concomitantly. These findings establish that, under appropriate conditions, uranium(III) can mediate a complete synthetic cycle for the homologation of CO to higher derivatives. This work may prove useful in spurring wider efforts in CO homologation, and the simplicity of this system suggests that catalytic CO functionalization may soon be within reach.reduction | C-C coupling | ethyne diolate | antiferromagnetic exchange coupling T he continued growth and stability of the global economy requires the ready availability of petrochemical feedstocks, but uncertainty in cost and supply, underscored by the energy crisis in the 1970s, has driven the demand for developing alternative sources (1). CO is readily produced by steam reforming reactions and is, thus, an abundant resource that can be used in the production of bulk hydrocarbon feedstocks (2). The concept of directly homologating CO is very appealing, but the triple bond in CO is very strong with a bond energy of ∼257 kcal mol −1 , and direct dimerization of CO to O ¼ C ¼ C ¼ O is highly unfavorable with ΔG°2 98 K ≈ þ73 kcal mol −1 (3). Although direct 1,1-migratory insertion of CO into an organometallic M-R bond to give M-C(O)R is a favorable process for many metals (4) and a key step in industrially important C-C bond formation reactions, e.g., hydroformylation (5), double insertion to give M-C(O)C(O)R is usually energetically unfeasible, but it has been documented (6-8). Thus, processes involving CO can require energy intensive reaction conditions and give varied product distributions that render them economically uncompetitive overall when crude oil remains readily available; however, combining the coupling of CO with reduction results in a thermodynamically feasible process to give a family of oxocarbon dianions C n O n 2− (n ¼ 2-6), including the reductively dimerized ethyne diolate − O-C ≡ C-O − , as building blocks for more complex and value-added organic molecules (9).Molten potassium can effect reductive oligomerization of CO, but the resulting ill-defined salts are thermally unstable and shock-sensitive (10). CO can be electrochemically homologated, but an overpressure of 100-400 bar of CO is required (11). Very few transition metal complexes mediate the reductive coupling...

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Section: Resultssupporting

confidence: 92%

Homologation and functionalization of carbon monoxide by a recyclable uranium complex

Gardner

Stewart

Davis

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

163

110

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“…[1] In particular, 1,3-Diynes have a rod-like molecular shape and high rigidness, which play important roles in the construction of molecular complexes and serve as connectors to build up conjugated polymers, liquid crystals, and nonlinear optic materials, etc. [2] , [3] Given their significance, synthesis of 1,3-Diynes has attracted a great deal of attention. The most widely used procedure for preparing symmetrical diynes is the oxidative alkyne homocoupling reaction.…”

Section: Introductionmentioning

confidence: 99%

Structure–property relationships of copper modified mesoporous TiO2 materials on alkyne homocoupling reactions

Luo

Cetegen

Miao

et al. 2016

Journal of Catalysis

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Three different modification (doping, solvent free, and impregnation) methods were used to obtain a series of mesoporous Cu-TiO 2 materials with various copper loading amounts (0 to 15 mol %). The influence of the modification procedure on the physico-chemical properties was characterized by PXRD, N 2 sorption, SEM, EDX elemental mapping, and XPS techniques. The presence of copper species have been detected either in the TiO 2 lattice as Cu + (via doping methods) or on the surface of TiO 2 as CuO species (via solvent free and impregnation methods). With the modification of Cu, the surface area of mesoporous Cu-TiO 2 materials can be increased up to 128 m 2 /g. The catalytic activities of Cu-TiO 2 materials were investigated using the alkyne-alkyne homocoupling reaction with air as the sole oxidant under mild reaction conditions without any additives. The doped Cu-TiO 2 materials show the highest catalytic activity (1,4-diphenyl-1,3-butadiyne yields > 99%). The different catalytic mechanisms, active sites, and structure-property relationships of all the catalysts are discussed. Definitive features affecting the catalytic performance of the obtained Cu-TiO 2 materials are the loading amounts and the states of Cu, surface area, and pore size distributions. Reusability tests were conducted on the collected sample without washing, and 74% yield was achieved even after three cycles.

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“…As coupling partners, internal and terminal alkynes (alkyne II) such as 3-hexyne (2 a), bis(trimethylsilyl)acetylene (2 b), tolane (2 c) and (trimethylsilyl)acetylene (2 d) were employed ( Table 2). [18] Notably, even highly sterically encumbered alkynes II such as 2 b and 2 c were successfully converted. Alkynes I with a sterically demanding substituent were found to be difficult substrates in the intermolecular domino reaction.…”

Section: Markus Leibelingmentioning

confidence: 99%

Intermolecular Twofold Carbopalladation/Cyclization Sequence to Access Chromans and Isochromans from Carbohydrates

Leibeling

Milde

Kratzert

et al. 2011

Chemistry A European J

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Alkynes Between Main Group Elements: From Dumbbells via Rods to Squares and Tubes

Cited by 83 publications

References 416 publications

Homologation and functionalization of carbon monoxide by a recyclable uranium complex

Homologation and functionalization of carbon monoxide by a recyclable uranium complex

Structure–property relationships of copper modified mesoporous TiO2 materials on alkyne homocoupling reactions

Intermolecular Twofold Carbopalladation/Cyclization Sequence to Access Chromans and Isochromans from Carbohydrates

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