Concave Butterfly-Shaped Organometallic Hydrocarbons?

Laskoski, Matthew; Roidl, Gaby; Smith, Mark D.; Bunz, Uwe H. F.

doi:10.1002/1521-3757(20010417)113:8<1508::aid-ange1508>3.0.co;2-7

“…ORTEP representations of 7, 12 , and 17 , and the packing diagram of 12 are shown in Figures 1–3 , , . The bond lengths and bond angles in 7, 12 , and 17 are in excellent agreement with the reported values for alkynylated cyclobutadiene and cyclopentadienyl complexes 13, 20…”

Section: Methodssupporting

confidence: 88%

“…The butadiyne groupings are moderately bent to accommodate the topological requirements of the structure (Figure 1). The substituents (i.e., spokes and periphery of the large hydrocarbon ligand) on the cyclobutadiene complex are considerably less nonplanar than expected for multiply ethynylated complexes of this type 13, 20. This effect may be a consequence of the direct interconnection of the three alkyne substituents by a network of cyclyne rings.…”

Section: Methodsmentioning

confidence: 93%

“…Rewards are expected in materials properties that differ from their organic counterparts, such as electroactivity and potential nonlinear optics (NLO) activity. In addition, large carbon‐rich organometallic molecules are often surprisingly soluble and form single crystals, which allows their structural characterization in the solid state,13 a feature that is often elusive for their organic counterparts.…”

Section: Methodsmentioning

confidence: 99%

“…The structures of the open congeners of 17 and of the butterfly 18 have been described recently 13. In these species the alkyne bridges are bent away from the cyclobutadiene nucleus to accommodate for the electronic influence of the {CpCo} fragment.…”

Section: Methodsmentioning

confidence: 99%

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Synthesis and Structural Characterization of Organometallic Cyclynes: Novel Nanoscale, Carbon-Rich Topologies

Laskoski

¹

,

Steffen

²

,

Morton

³

et al. 2002

Angew. Chem. Int. Ed.

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Dedicated to Professor G¸nther E. Szeimies ™Carbon-rich∫ defines an exciting area that spans the world of large arenes to that of highly alkynylated structures including carbon wires, peralkynylated p perimeters, graphdiyne segments, dehydroannulenes, and cyclophane derivatives. [1±9] Carbon-rich organometallic compounds are less explored than their organic counterparts, a tribute to the considerably increased effort in their synthetic access. [10±14] Aesthetic structures, exciting topologies on the nanometer scale, and their modular synthesis, however, make carbon-rich organometallic compounds attractive. Rewards are expected in materials properties that differ from their organic counterparts, such as electroactivity and potential nonlinear optics (NLO) activity. In addition, large carbon-rich organometallic molecules are often surprisingly soluble and form single crystals, which allows their structural characterization in the solid state, [13] a feature that is often elusive for their organic counterparts.Herein we report the synthesis and structural characterization of three novel organometallic cyclynes [10] with an expanded bicyclo[1.1.0]butane (A) and a [2.1.0.0 1,3 ]pentane (B) topology. In these structures, the CÀC single bonds of the small rings are replaced by alkyne or butadiyne bridges, while the carbon atoms are substituted by benzene rings, cyclobutadiene(cyclopentadienylcobalt) units, or ferrocene centers. Key steps in the synthesis of these targets are the selective ortho-metalation of organometallic acetals, [14] and the conversion of aldehydes into alkynes by the Ohira method. [15] Pd-catalyzed coupling of 1 [14] to the iodide 2 a furnishes 3 in 23 % (Scheme 1). The moderate yield of 3 is a result of the two meta-positioned alkyne groups in 2 a between which the iodide is sandwiched. Only the active Hartwig catalyst epoxide synthesis. A study of other ligands to expand the scope of the process and enhance asymmetric induction, as well as synthetic applications, is currently underway. Experimental SectionTypical procedure for lithiation ± electrophile trapping of cyclooctene oxide (1) in the presence of a diamine:The diamine (2.6 mmol) was added dropwise to a solution of RLi (1.4 m, 2.5 mmol) in Et 2 O (8 mL) at À 90 8C. This mixture was stirred for 1 h at À 90 8C. A solution of cyclooctene oxide (1; 2.0 mmol) in Et 2 O (2 mL), precooled to À 90 8C, was then added rapidly by cannula to the solution of ligand/RLi and the reaction mixture was then stirred at À 90 8C for 3 h. Neat electrophile (3.0 mmol) was added dropwise, and the mixture was then allowed to warm to room temperature over 5 h. After quenching with aqueous H 3 PO 4 (0.5 m, 25 mL), the organic phase was washed with saturated aqueous NaHCO 3 (25 mL) and brine (25 mL). The aqueous layers were extracted twice with Et 2 O (25 mL) and the combined organic phases were dried (MgSO 4 ) and evaporated under reduced pressure. Purification of the residue by column chromatography (SiO 2 , Et 2 O, petrol) gave the substituted epoxide.

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“…and related dehydro [14]annulenes incorporating the bis(trimethylsilyl)cyclobutadiene-(cyclopentadienyl-cobalt) moiety suggest that the aromaticity of the fused cyclobutadiene complex might be stronger than that of benzene according to the ring-current criterion. The butterfly complex 92 [50] and the ferrocene derivative 93 [51] (Scheme 21) were synthesized by comparable coupling routes, starting from the building blocks 51 and 52, respectively. According to X-ray structural analysis, complexes such as 92 possess a concave structure and are of interest since the tetraethynylcyclobutadiene motif has been to suggested to play an important role in the formation of fullerenes such as C 60 [52].…”

Section: H Nmr Analysis Of Thismentioning

confidence: 99%

From Acetylenes to Aromatics: Novel Routes – Novel Products

Hopf

¹

2002

Modern Arene Chemistry

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Alkynes have been used as precursors for aromatic compounds since Berthelot converted acetylene to benzene in 1867. The review presents new evidence on the mechanism of this first total synthesis of an aromatic compound. Presumably, its last step involves the thermocyclization of hexa-1,3-dien-5-yne to benzene. Trapping experiments as well as the study of derivatives of this highly unsaturated hydrocarbon show that the reaction takes place via isobenzene intermediates (1,2,4-cyclohexatrienes) at lower temperatures. Under high temperature pyrolysis conditions, carbenes as well as radical routes compete with the pericyclic process. In another recent application of acetylenes in the synthesis of aromatic compounds,

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Synthesis and Structural Characterization of Organometallic Cyclynes: Novel Nanoscale, Carbon-Rich Topologies

Laskoski

¹

,

Steffen

²

,

Morton

³

et al. 2002

View full text Add to dashboard Cite

Dedicated to Professor G¸nther E. Szeimies ™Carbon-rich∫ defines an exciting area that spans the world of large arenes to that of highly alkynylated structures including carbon wires, peralkynylated p perimeters, graphdiyne segments, dehydroannulenes, and cyclophane derivatives. [1±9] Carbon-rich organometallic compounds are less explored than their organic counterparts, a tribute to the considerably increased effort in their synthetic access. [10±14] Aesthetic structures, exciting topologies on the nanometer scale, and their modular synthesis, however, make carbon-rich organometallic compounds attractive. Rewards are expected in materials properties that differ from their organic counterparts, such as electroactivity and potential nonlinear optics (NLO) activity. In addition, large carbon-rich organometallic molecules are often surprisingly soluble and form single crystals, which allows their structural characterization in the solid state, [13] a feature that is often elusive for their organic counterparts.Herein we report the synthesis and structural characterization of three novel organometallic cyclynes [10] with an expanded bicyclo[1.1.0]butane (A) and a [2.1.0.0 1,3 ]pentane (B) topology. In these structures, the CÀC single bonds of the small rings are replaced by alkyne or butadiyne bridges, while the carbon atoms are substituted by benzene rings, cyclobutadiene(cyclopentadienylcobalt) units, or ferrocene centers. Key steps in the synthesis of these targets are the selective ortho-metalation of organometallic acetals, [14] and the conversion of aldehydes into alkynes by the Ohira method. [15] Pd-catalyzed coupling of 1 [14] to the iodide 2 a furnishes 3 in 23 % (Scheme 1). The moderate yield of 3 is a result of the two meta-positioned alkyne groups in 2 a between which the iodide is sandwiched. Only the active Hartwig catalyst epoxide synthesis. A study of other ligands to expand the scope of the process and enhance asymmetric induction, as well as synthetic applications, is currently underway. Experimental SectionTypical procedure for lithiation ± electrophile trapping of cyclooctene oxide (1) in the presence of a diamine:The diamine (2.6 mmol) was added dropwise to a solution of RLi (1.4 m, 2.5 mmol) in Et 2 O (8 mL) at À 90 8C. This mixture was stirred for 1 h at À 90 8C. A solution of cyclooctene oxide (1; 2.0 mmol) in Et 2 O (2 mL), precooled to À 90 8C, was then added rapidly by cannula to the solution of ligand/RLi and the reaction mixture was then stirred at À 90 8C for 3 h. Neat electrophile (3.0 mmol) was added dropwise, and the mixture was then allowed to warm to room temperature over 5 h. After quenching with aqueous H 3 PO 4 (0.5 m, 25 mL), the organic phase was washed with saturated aqueous NaHCO 3 (25 mL) and brine (25 mL). The aqueous layers were extracted twice with Et 2 O (25 mL) and the combined organic phases were dried (MgSO 4 ) and evaporated under reduced pressure. Purification of the residue by column chromatography (SiO 2 , Et 2 O, petrol) gave the substituted epoxide.

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Concave Butterfly-Shaped Organometallic Hydrocarbons?

Cited by 10 publications

References 29 publications

Synthesis and Structural Characterization of Organometallic Cyclynes: Novel Nanoscale, Carbon-Rich Topologies

Synthesis and Structural Characterization of Organometallic Cyclynes: Novel Nanoscale, Carbon-Rich Topologies

From Acetylenes to Aromatics: Novel Routes – Novel Products

Synthesis and Structural Characterization of Organometallic Cyclynes: Novel Nanoscale, Carbon-Rich Topologies

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