Organopalladium approaches to prostaglandins. 1. Synthesis of thiophene-containing prostaglandin endoperoxide analogs via thienylpalladation of bicycle olefins

Larock, Richard C.; LEACH, D. R.; Bjorge, S. M.

doi:10.1016/s0040-4039(00)86929-4

Cited by 28 publications

(4 citation statements)

References 2 publications

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“…10 However, certain reactions involving palladium and norbornadiene (bis olefin) have been found to result in endo insertion, 24 while others yield products that have isomerized to a nortricyclyl skeleton. 25 For our products, NMR chemical shifts appear to be consistent with a cis, exo arrangement of the phenyl rings (based on assignments made on similar compounds in the literature 4 ). This stereochemical assignment was unambiguously confirmed with an X-ray crystallographic analysis on compound 1a (Supporting Information).…”

supporting

confidence: 75%

“…Finally, in terms of the stereochemistry of the products, other researchers have found analogous ternary reactions with norbornene (mono olefin) to proceed in a cis , exo fashion . However, certain reactions involving palladium and norbornadiene (bis olefin) have been found to result in endo insertion, while others yield products that have isomerized to a nortricyclyl skeleton . For our products, NMR chemical shifts appear to be consistent with a cis , exo arrangement of the phenyl rings (based on assignments made on similar compounds in the literature 4 ).…”

supporting

confidence: 70%

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Tandem Suzuki Coupling−Norbornadiene Insertion Reactions. A Convenient Route to 5,6-Diarylnorbornene Compounds

Shaulis¹,

Hoskin²,

Townsend³

et al. 2002

J. Org. Chem.

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supporting

confidence: 75%

supporting

confidence: 70%

Tandem Suzuki Coupling−Norbornadiene Insertion Reactions. A Convenient Route to 5,6-Diarylnorbornene Compounds

Shaulis¹,

Hoskin²,

Townsend³

et al. 2002

J. Org. Chem.

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“…A number of species have been reported containing a bond or interaction between palladium and the sulfur of a thiophene ring; [18][19][20][21][22][23][24][25][26] however, only two of these have been structurally characterized. 25,26 distance is 2.427(3) Å.…”

Section: Resultsmentioning

confidence: 99%

“…A number of species have been reported containing a bond or interaction between palladium and the sulfur of a thiophene ring; − however, only two of these have been structurally characterized. , In [Pd(SDPDTP)]Cl (SDPDTP = 5,20- diphenyl-10,15-ditolyl-21-thiaporphyrin), the Pd−S bond length (2.208(5) Å) is shorter than the corresponding bond in 5c and shorter than the sum of the covalent radii of Pd and S (2.35 Å) . On the other hand, in [Pd(μ-C 3 H 5 )(L)][CF 3 SO 3 ] (L = 2,5,8-trithia[9](2,5)thiophenophane), the Pd−S (thiophene) distance (2.786(4) Å) is much longer than both the Pd−S bond in 5c and the sum of the covalent radii; however, because the Pd−S distance is shorter than the sum of the van der Waals radii (3.4 Å), an apical Pd−S bond was postulated .…”

Section: Resultsmentioning

confidence: 99%

Electropolymerization of Pd(II) Complexes Containing Phosphinoterthiophene Ligands

2001

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A series of Pd complexes of 3'-diphenylphosphino-2,2':5'2' '-terthiophene (1a, dppterth) in which the metal is coordinated in three different modes have been prepared and electropolymerized, resulting in the formation of conductive thin films. In [Pd2(mu-Cl2)(dppterth-P,C3)2] (3a) the metal is P,C-coordinated, in [PdCl2(dppterth-P)2] (4a) the coordination is monodentate via the phosphine, and in [Pd(dppterth-P,C3)(dppterth-P,S1)][PF6] (5a) both P,C- and P,S-coordination modes are found. In 5a, the coordinated thiophene is hemilabile and may be displaced by reaction with more strongly coordinating ligands such as isocyanides. To probe the effect of blocking the alpha-position of the terthienyl moiety with methyl groups, 3'-diphenylphosphino-5-methyl-2,2':5'2' '-terthiophene (1b, Me-dppterth) and 3'-diphenylphosphino-5,5' '-dimethyl-2,2':5'2' '-terthiophene (1c, Me2-dppterth) were prepared, and the corresponding series of Pd complexes was synthesized. One of these complexes, [Pd(Me2-dppterth-P,C3)(Me2-dppterth-P,S1)][PF6] (5c), has been crystallographically characterized. The electropolymerized films prepared from 5a react with isonitriles, and shifts in the absorption spectra of the electropolymerized materials are observed upon reaction. A Pd complex has also been prepared from 5-diphenylphosphino-2,2':5'2' '-terthiophene (2, 5dppterth), and this complex has been electropolymerized. All the electropolymerized thin films have been characterized using EDX analysis, which demonstrates good correspondence with the elemental analysis of the respective monomers, and the maximum conductivities of the films are near 10(-4) S x cm(-1). Comparing the electropolymerization behavior of the complexes, along with their electrochemical and spectroscopic data, allows conclusions to be drawn regarding the involvement of pi-delocalization and the metal group in the conductivity of the materials.

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Organocopper Reagents: Substitution, Conjugate Addition, Carbo/Metallocupration, and Other Reactions

1992

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Well over a decade ago, two reviews were contributed to the Organic Reactions series covering substitution and conjugate addition reactions in organocopper chemistry. Their appearance, which highlighted most of the early work in this field, served not only as a source of invaluable references to original literature reports, but also stimulated a vast number of subsequent studies on the properties and uses of organocopper complexes. The work cited in this chapter, which dates from ca. 1975, concerns in large measure uses of organocopper complexes originating from either catalytic or stoichiometric quantities of a copper(I) halide together with a Grignard (RMgX) or organolithium (RLi) reagent. These combinations form either neutral organocopper reagents RCu ( 1 ) or copper(I) monoanionic salts R 2 CuM (M = Li or MgX), commonly referred to as “lower‐order” species. The latter ate complexes with lithium as gegenion ( 2 ) are also known as “Gilman reagents” in recognition of their origins. Copper(I) cyanide is also an excellent precursor, affording homogeneous mixtures of lower order cyanocuprates RCu(CN)Li, ( 3 ), upon treatment with an equivalent of an organolithium. The strength of the CuCN linkage presumably accounts for direct cuprate formation with 1 equivalent of the organolithium, rather than the metathesis that occurs with copper(I) chloride, bromide, or iodide. While use of reagents ( 1 ), ( 2 ) and ( 3 ) alone can be aptly classified as broad‐based and intense, their importance has further encouraged extensive development of variations on these themes (i.e., their composition and reactivity profiles). Reagents ( 1–3 ) have been found to be unexpectedly compatible with certain electrophilic additives at low temperatures, which substantially alter their reactivity. Rather than forming ( 2 ) from 2 equivalents of the same RLi, different organolithiums can be utilized to give R T R R CuLi, ( 4 ), conserving potentially valuable RLi. This scenario raises the question of controlling the selectivity of transfer of the desired ligand R T rather than the anticipated residual (or “dummy”) group R R from copper to electrophilic carbon. Fortunately, many solutions to this problem now exist. Admixture of 2RLi (or R T Li + R R Li) with copper(I) cyanide proceeds beyond the stage of ( 3 ) to ultimately arrive at copper(I) dianionic complexes 5 , the so‐called “higher‐order” cyanocuprates. Undoubtedly it is the cyano ligand, with its π‐acidic nature, which enables copper to accept a third negatively charged ligand. Although reagents ( 5 ) do not yet share in all of the benefits offered by time in comparison with their lower‐order counterparts, they nicely complement prior art. Moreover, as with species ( 1–4 ), they continue to evolve, providing the synthetic community with alternatives for highly selective and efficient means of making key carbon–carbon bonds.

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Organopalladium approaches to prostaglandins. 1. Synthesis of thiophene-containing prostaglandin endoperoxide analogs via thienylpalladation of bicycle olefins

Cited by 28 publications

References 2 publications

Tandem Suzuki Coupling−Norbornadiene Insertion Reactions. A Convenient Route to 5,6-Diarylnorbornene Compounds

Tandem Suzuki Coupling−Norbornadiene Insertion Reactions. A Convenient Route to 5,6-Diarylnorbornene Compounds

Electropolymerization of Pd(II) Complexes Containing Phosphinoterthiophene Ligands

Organocopper Reagents: Substitution, Conjugate Addition, Carbo/Metallocupration, and Other Reactions

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