Electrochemical investigation of the reducing power of SmI2 in THF and the effect of HMPA cosolvent

Shabangi, Masangu; Flowers, Robert A.

doi:10.1016/s0040-4039(97)00008-7

Cited by 191 publications

(90 citation statements)

References 12 publications

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“…Flowers and co-workers have studied the properties of a related SmBr 2 /HMPA complex, and found that the addition of HMPA to SmBr 2 results in a significant increase of the redox potential of the reagent (SmBr 2 : À2.07 V; SmBr 2 /HMPA: À2.63 V, both vs Ag/AgNO 3 in THF). [20] Enantiomerically pure 1,3-diols are useful building blocks for the synthesis of natural products. Zçrb and Brückner reported that SmBr 2 mediates a novel reduction of acetonides (generated by Sharpless asymmetric dihydroxylation) to give enantiomerically pure 3-hydroxy ketones (Scheme 7).…”

Section: Samarium(ii) Bromidementioning

confidence: 99%

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

2012

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Reactions proceeding through open-shell, single-electron pathways offer attractive alternative outcomes to those proceeding through closed-shell, two-electron mechanisms. In this context, samarium diiodide (SmI(2)) has emerged as one of the most important and convenient-to-use electron-transfer reagents available in the laboratory. Recently, significant progress has been made in the reductive chemistry of other divalent lanthanides which for many years had been considered too reactive to be of value to synthetic chemists. Herein, we illustrate how new samarium(II) complexes and nonclassical lanthanide(II) reagents are changing the landscape of modern reductive chemistry.

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Section: Samarium(ii) Bromidementioning

confidence: 99%

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

2012

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“…[3a, 12] Then, Inanaga found that the addition of hexamethyl phosphoramide (HMPA) [61] causes a remarkable increase in the reducing ability of SmI 2 ; SmI 2 with 4 equiv of HMPA has the highest reducing ability with an oxidation potential of À 2.05 V. [62] The resultant Sm III species may be used in situ as a Lewis acid catalyst. In turn, the Sm III species can be reduced to an Sm II species to complete the catalytic process and regeneration of not only SmI 2 but also of the chiral ligands coordinated to the Sm II/III center ( Figure 11).…”

Section: Reagents and Reactionsmentioning

confidence: 99%

“Asymmetric” Catalysis by Lanthanide Complexes

Mikami

Terada

Matsuzawa

2002

Angew. Chem. Int. Ed.

232

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velopment of asymmetric Ln catalysts, and their recyclable use, is of increasing importance. This review gives an overview of the most recent developments in catalysis with lanthanide(ii) and lanthanide(iii) complexes. REVIEWS[ + ] The elements specified in Figure 1 include scandium and yttrium, which are not formally defined as lanthanide elements, but as rare earth metals. For the sake of simplicity, in this review these two elements are also abbreviated to Ln.

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“…7 According to Flowers and coworkers, the oxidation potential of SmI2 alone is −1.33 V (vs. Ag/AgNO3 in THF), and was found to increase to a maximum of −2.05 V with four equivalents of added HMPA. 9 When these conditions were applied to the intramolecular coupling reaction, an increase in selectivity toward cyclization over aldehyde reduction was observed (Table 1, entry 2).…”

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confidence: 99%

Synthesis of Tetrahydroisoquinocarbazoles via C-2 Alkylation of Indoles with 2-Alkoxycyclopropanoate Esters

Bajtos

Pagenkopf

2009

Org. Lett.

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A concise method for the synthesis of several tetrahydroisoquinocarbazole derivatives is reported, where the core is prepared in six steps from tryptophol in 51% overall yield. The pentacyclic analogs are constructed via a dipolar C-2 alkylation of a 3-substituted indole with a 2-alkoxycyclopropanoate ester and a SmBr 2 -HMPA mediated ketyl-alkene ring closure.Considerable synthetic attention has been directed at the development of efficient methods toward the construction and derivatization of indole-containing compounds, as this important subunit constitutes the core of a plethora of biologically active natural products. 1 Our research group has recently developed a methodology for C-2 alkylation of 3-substituted indoles with 2-alkoxycyclopropanoate esters to give useful indole products, 2 complete with ester and alkene functional group handles for further synthetic manipulation.Biologically active, fused indole compounds such as the vinca alkaloids have inspired synthetic and medicinal interest in a large class of related tetrahydroisoquinocarbazole analogues, most of which exhibit antiarrhythmic activity. 3,4 Among the most potent members of this class, RS-2135 has attracted the most attention because of its relatively low toxicity. In the only synthetic approach to these compounds

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Electrochemical investigation of the reducing power of SmI2 in THF and the effect of HMPA cosolvent

Cited by 191 publications

References 12 publications

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

“Asymmetric” Catalysis by Lanthanide Complexes

Synthesis of Tetrahydroisoquinocarbazoles via C-2 Alkylation of Indoles with 2-Alkoxycyclopropanoate Esters

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