Addition of Nitrile Oxides to Silyl- And Germyl-Disubstituted Ethylenes

Lukevics, É.; Arsenyan, Pavel; Fleisher, M.; Popelis, J.; Pudova, Olga

doi:10.1515/mgmc.1999.22.11.655

Cited by 7 publications

(6 citation statements)

References 15 publications

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“…Although 6 is fully compatible with silica gel chromatography, this highly versatile 10 new building block can also be conveniently isolated in excellent purity by recrystallization. One-pot hydrostannylation 14 of 6 followed by iododestannylation of the resulting bis-metalated intermediate provided an excellent yield of ( E )- 1 . Alternatively subjecting 6 to a series of silver-promoted alkyne iodination 12 followed by PADC-mediated semireduction 13 provided the complementary building block ( Z )- 1 .…”

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confidence: 99%

“…A synthesis of ( E )- 2 has been previously reported, 6 but a stereocontrolled route to ( Z )- 2 was unknown. 14 As shown in Scheme 4 , hybridizing methodology previously reported for the germylstannylation of substituted alkynes 15 and the silylstannylation of acetylene, 16 core building block ( Z )- 2 was efficiently prepared as a single stereoisomer by the palladium-mediated cis -germylstannylation of acetylene gas.…”

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A Simple and General Platform for Generating Stereochemically Complex Polyene Frameworks by Iterative Cross‐Coupling

2010

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A Simple and General Platform for Generating Stereochemically Complex Polyene Frameworks by Iterative Cross‐Coupling

2010

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“…A synthesis of ( E )‐ 2 has been previously reported,6 but a stereocontrolled route to ( Z )‐ 2 was unknown 14. As shown in Scheme , hybridizing methodology previously reported for the germylstannylation of substituted alkynes15 and the silylstannylation of acetylene,16 core building block ( Z )‐ 2 was efficiently prepared as a single stereoisomer by the palladium‐mediated cis ‐germylstannylation of acetylene gas.…”

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confidence: 97%

A Simple and General Platform for Generating Stereochemically Complex Polyene Frameworks by Iterative Cross‐Coupling

2010

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Aiming to maximally harness the inherent modularity of small molecules, we are pursuing the development of a synthesis strategy based on the iterative cross-coupling (ICC) of bifunctional building blocks representing the substructures that most commonly appear in natural products. [1, 2] In this vein, various combinations of trans-and cis-olefins are found in many small molecules derived from a wide range of biosynthetic pathways, including polyketides, hybrid peptide/ polyketides, polyterpines, and fatty acids (Scheme 1). [3,4] Enabling stereospecific access to these stereochemically complex polyene frameworks, we herein describe the development of a novel ICC platform that yields bifunctional iodopolyenyl N-methyliminodiacetic acid (MIDA) boronates in all possible stereoisomeric forms. The power of this approach has been realized in the first synthesis of the highly complex (E,E,E,Z,Z,E,E)-heptaene framework of the ion channel-forming polyene macrolide vacidin A.We recently reported three haloalkenyl MIDA boronates that enabled the preparation of a subset of polyene motifs by ICC.[2b] Albeit an important step forward, this collection only provided access to all-trans-polyene substructures and utilized polyenylchlorides. Accessing stereochemically complex polyene motifs is substantially more challenging because, in addition to the sensitivities observed with all polyenes to light, oxygen, and acid, frameworks containing cis double bonds can isomerize to the typically more thermodynamically stable all-trans structures. Moreover, poorly reactive polyenylchlorides proved to be minimally effective in complex applications.To overcome both of these limitations, we pursued a novel strategy for making iodopolyenyl MIDA boronates by ICC of iodide-masked [5] bifunctional building blocks. As shown in Scheme 2 A, the approach involves metal-selective crosscoupling of Sn/Ge bis-metalated olefins [6] to generate polyenylgermanium intermediates followed by stereospecific iododegermylations. [7] To the best of our knowledge, iododegermylations of polyenylgermanium species were unreported. However, the facility of halodegermylation [7] vs. halodesilylation [8] of simple olefins suggested that the former process had superior potential to be efficient and stereoretentive in the context of structurally and stereochemically complex polyene systems. Guided by this logic, we hypothesized that iterative cycles of metal-selective coupling/iododegermylation with core building blocks 1 and 2 (Scheme 2 B) could Scheme 1. Polyene natural products derived from a wide range of biosynthetic pathways. Scheme 2. A) A strategy for ICC of halogen-masked bifunctional building blocks. B) Core building blocks to enable general access to stereoisomeric iodopolyenyl MIDA boronates. C) New iodopolyenyl MIDA boronates for the synthesis of polyene natural products.

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“…The germanium atom does not bridge the Co-Co bond symmetrically, it is displaced slightly from the Co 4 plane, the dihedral angle between the GeCoCo triangle and the Co 4 plane being 8.1°. Atom Si (2 ) symmetrically positioned between Co (2) and Co (3) is closer to Co (1) , and slightly further from Co (4) . Atom Si (1) is closer to Co (1) and Co (3) while further from Co (2) and Co (4) .…”

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“…According to X-ray diffraction the gold complex 13 [47] has dimeric structure, as a result of additional Au-Au bonding and partial migration of the di(diphenylphosphino)methylene (dppm) (1) and Au (2) and Fe (2) and Au (1) each bridged by a dppm ligand, thus forming two unusual, twisted six-membered rings fused along the Au-Au edge. The coordination geometry of the iron atoms may be described as distorted octahedral with the Ρ and Si atoms trans to one another and the CO ligands in a merarrangement.…”

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MOLECULAR STRUCTURE OF ORGANOSILICON COMPOUNDS WITH Si-Fe, Si-Co AND Si-Ni BONDS

Lukevics¹,

Pudova²

2000

Main Group Metal Chemistry

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The results of the structural investigations of the group 8 metal derivatives containing the direct Si-Fe, Si-Co, Si-Ni bonds are summarized in the present review. IntroductionRecently we have published a comprehensive survey of data on the molecular structure of organosilicon compounds with Si-Si [1], Si-Ge, Si-Sn, Si-Pb, Si-Ti, Si-Zr, and Si-Hf bonds [2], as a part of the structural investigations related to the silyl substituted metal derivatives. Herein, we present a review concerning the molecular structure of iron, cobalt and nickel derivatives bearing silyl substituents at the metal atoms. Compounds with transition metal-silicon bonds have been the focus of a considerable interest and there has been remarkable progress over the last few years in the preparation of complexes containing silyl and silylene ligands. This is largely motivated by the possibility to stabilize complexes otherwise unstable, the occurrence of unusual structures, novel reactivity patterns and the construction of clusters having direct metal-metal bonds. These complexes are characterized by a very rich chemistry and have important applications in a number of catalytic processes.

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Addition of Nitrile Oxides to Silyl- And Germyl-Disubstituted Ethylenes

Cited by 7 publications

References 15 publications

A Simple and General Platform for Generating Stereochemically Complex Polyene Frameworks by Iterative Cross‐Coupling

A Simple and General Platform for Generating Stereochemically Complex Polyene Frameworks by Iterative Cross‐Coupling

A Simple and General Platform for Generating Stereochemically Complex Polyene Frameworks by Iterative Cross‐Coupling

MOLECULAR STRUCTURE OF ORGANOSILICON COMPOUNDS WITH Si-Fe, Si-Co AND Si-Ni BONDS

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