Stereoselective Synthesis of Tri- and Tetrasubstituted Olefins by Tandem Cyclization Addition Reactions Featuring Vinyl Radicals

Gansäuer, Andreas; Pierobon, Marianna; Bluhm, Harald

doi:10.1002/1521-3773(20020902)41:17<3206::aid-anie3206>3.0.co;2-2

Cited by 83 publications

(31 citation statements)

References 33 publications

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“…[1] A number of different catalytic methods have been developed to synthesize tetrasubstituted olefins, including: Suzuki-type Pd-catalyzed coupling reactions, [2] Ni- and Rh-catalyzed exocyclization methods, [3] Ni- and Pd-catalyzed nucleophilic coupling reactions of alkynes [4] and of alkyne-to-arylboronic acids, [5] Ti-catalyzed tandem alkyne-epoxide-ethyl acetate coupling, [6] and the ring-closing olefin metathesis by using Grubbs catalyst. [7] Though catalytic conjugate addition of alkenes has been recognized as a potentially powerful synthetic methodology in forming tetrasubstituted olefins, generally applicable conjugate addition of simple olefins to α,β-unsaturated carbonyl compounds has been hampered by lack of reactivity of the olefin substrates and due to the formation of homocoupling and other byproducts.…”

mentioning

confidence: 99%

Tetrasubstituted Olefins through the Stereoselective Catalytic Intermolecular Conjugate Addition of Simple Alkenes to α,β‐Unsaturated Carbonyl Compounds

Kwon¹,

Lee²,

Yi³

2011

Angew Chem Int Ed

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Recent efforts in designing expeditious catalytic synthesis of tetrasubstituted olefins have in part been stimulated by growing needs for developing generally applicable methods for tamoxifen analogs (anti-breast cancer drug) as well as for photo-responsive organic materials and molecular devices.[1] A number of different catalytic methods have been developed to synthesize tetrasubstituted olefins, including: Suzuki-type Pd-catalyzed coupling reactions,[2] Ni- and Rh-catalyzed exocyclization methods,[3] Ni- and Pd-catalyzed nucleophilic coupling reactions of alkynes[4] and of alkyne-to-arylboronic acids,[5] Ti-catalyzed tandem alkyne-epoxide-ethyl acetate coupling,[6] and the ring-closing olefin metathesis by using Grubbs catalyst.[7] Though catalytic conjugate addition of alkenes has been recognized as a potentially powerful synthetic methodology in forming tetrasubstituted olefins, generally applicable conjugate addition of simple olefins to α,β-unsaturated carbonyl compounds has been hampered by lack of reactivity of the olefin substrates and due to the formation of homocoupling and other byproducts. Chelate-assisted C–H insertion[8] and cross coupling methods[9] are among the most notable advances in catalytic coupling reaction of enones with simple alkenes. Ni-catalyzed conjugate addition and allylic substitution reactions of simple alkenes have also been reported recently.[10] We recently discovered that the cationic complex [(C6H6)(CO)(PCy3)RuH]+BF4− (1) is a highly effective catalyst precursor for the coupling reactions of arylketones and alkenes involving C–H activation.[11] Herein we report a novel catalytic synthesis of tetrasubstituted olefins from the intermolecular conjugate addition reaction of simple olefins to α,β-unsaturated carbonyl compounds.

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confidence: 99%

Tetrasubstituted Olefins through the Stereoselective Catalytic Intermolecular Conjugate Addition of Simple Alkenes to α,β‐Unsaturated Carbonyl Compounds

Kwon¹,

Lee²,

Yi³

2011

Angew Chem Int Ed

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“…On treatment with Cp 2 TiCl 2 , compound 161 generates a reactive vinyl radical after cyclization, and this then adds to the acrylate to form product 163 with high diastereoselectivity [52]. The steric interactions between the catalyst and the acrylate are important for the selectivity.…”

Section: Titanocene-mediated Radical Cyclizationsmentioning

confidence: 99%

Radical Reactions

Patil¹,

Sibi²

2005

Quaternary Stereocenters

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“…Unfortunately, this is not always the case as shown in Table 1. [37] Models explaining the observed selectivities can be obtained from a simple analysis of transition structures according to Spellmeyer×s and Houk×s work. [38] These authors have calculated the transition states for cyclisations of radicals like the ones shown in Scheme 19 but with a hydrogen atom being replaced by the CH 2 OTiCp 2 Cl group.…”

Section: Reviewsmentioning

confidence: 99%

“…With nonterminal alkynes as acceptors the olefinic isomers are generated as mixtures of (E)-and (Z)-isomers in high yields but with low selectivity. [37] …”

Section: Reviewsmentioning

confidence: 99%

Titanocene-Catalysed Electron Transfer-Mediated Opening of Epoxides

Gansäuer

Narayan

2002

Advanced Synthesis & Catalysis

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The use of epoxides as substrates for radical reactions via electron transfer is described. The discussion of the evolution of stoichiometric reagents focuses on recent developments in the field of titanocene(III) reagents. Special attention is devoted to the emergence of catalytic conditions for this useful procedure that has led to the discovery of reagent‐controlled radical reactions by variations of the cyclopentadienyl ligands.

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Stereoselective Synthesis of Tri- and Tetrasubstituted Olefins by Tandem Cyclization Addition Reactions Featuring Vinyl Radicals

Cited by 83 publications

References 33 publications

Tetrasubstituted Olefins through the Stereoselective Catalytic Intermolecular Conjugate Addition of Simple Alkenes to α,β‐Unsaturated Carbonyl Compounds

Tetrasubstituted Olefins through the Stereoselective Catalytic Intermolecular Conjugate Addition of Simple Alkenes to α,β‐Unsaturated Carbonyl Compounds

Radical Reactions

Titanocene-Catalysed Electron Transfer-Mediated Opening of Epoxides

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