Regio‐ and Stereoselective Allylation and Crotylation of Indoles at C2 Through the Use of Potassium Organotrifluoroborate Salts

Nowrouzi, Farhad; Batey, Robert A.

doi:10.1002/anie.201207978

Cited by 63 publications

(44 citation statements)

References 44 publications

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“…Herein we report a Lewis acid promoted intramolecular aminocyanation of alkenes. We report the construction of 2,2-disubstituted indolines [20] and 2,2-disubstituted tetrahydroquinolines in an atom-economical fashion. The highlight of our approach is .…”

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confidence: 99%

Intramolecular Aminocyanation of Alkenes by NCN Bond Cleavage

et al. 2014

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A metal-free, Lewis acid promoted intramolecular aminocyanation of alkenes was developed. B(C 6 F 5 ) 3 activates N-sulfonyl cyanamides, thus leading to a formal cleavage of the NÀCN bonds in conjunction with vicinal addition of sulfonamide and nitrile groups across an alkene. This method enables atom-economical access to indolines and tetrahydroquinolines in excellent yields, and provides a complementary strategy for regioselective alkene difunctionalizations with sulfonamide and nitrile groups. Labeling experiments with 13 C suggest a fully intramolecular cyclization pattern due to the lack of label scrambling in double crossover experiments. Catalysis with Lewis acid is realized and the reaction can be conducted under air.

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confidence: 99%

Intramolecular Aminocyanation of Alkenes by NCN Bond Cleavage

et al. 2014

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“…Regioselective C-2 allylation of indoles has also been achieved by the use of catalysts such as Potassium organotrifluoroborate salts [7], Pd [8] and Rh [9] catalysts. Similarly selective synthesis of C-3 allylated indoles includes the use of catalysts such as H 2 SO 4 [10], Ru [11], amberlyst-15 [12], Et 3 B [13], Pd [14][15].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Regioselective N-allylation and N-cinnamylation of indoles using CuI-exchanged hierarchical nanoporous material

Senthilkumar¹,

Kumarraja²

2015

Catalysis Communications

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“…In our quest to fill this niche, we thought that the allylboration of indole would be a fertile proving ground. Allylborations at the C2 position of indole have been reported by the groups of Aggarwal, Batey, Bubnov, and our group . A formidable challenge is to realize these reactions by asymmetric catalysis.…”

Section: Optimization Of the Reaction Conditions For The Catalytic Asmentioning

confidence: 99%

Catalytic Asymmetric Allylboration of Indoles and Dihydroisoquinolines with Allylboronic Acids: Stereodivergent Synthesis of up to Three Contiguous Stereocenters

et al. 2016

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Abstract:The catalytic asymmetric allylboration of cyclic imines with g,g-disubstituted allylboronic acids provides products with adjacent stereocenters in high yield and stereoselectivity.V arious electrophiles,i ncluding 3,4-dihydroisoquinolines and indoles,were prenylated in afully stereodivergent fashion by switching the E/Z geometry of the allylboronate and/or the enantiomer of the BINOL catalyst. 3-Methylindole provided products with three adjacent stereocenters with high stereoselectivity in one synthetic operation.The allylboration reaction has become an indispensable method for the stereoselective synthesis of homoallylic alcohols and amines.[1] Recently,o ur group described the first catalytic asymmetric synthesis of homoallylic alcohols from g,g-disubstituted allylboronic acids and ketones,furnishing products bearing adjacent quaternary stereocenters. [2] Extending this reaction to imines for the synthesis of chiral amines with adjacent stereocenters is important as these motifs are common in drug-like molecules and natural products.[3] In addition, ac omparison of the asymmetric allylboration of ketones and imines using similar catalysts is highly interesting in terms of the stereoinduction.Although great progress has been made towards the allylboration of imines, [4] asymmetric examples have remained sparse.[5] Hoveyda [5f] and co-workers recently reported on the catalytic asymmetric allylboration of phosphinoyl imines,w hich provides access to enantioenriched products containing adjacent stereocenters.While this work is impressive,t he substrate scope is currently limited to monosubstitution at the g-position of the allylboronate,a nd only the anti products could be formed. Ac omplementary approach has been reported by the Aggarwal group [5g] for the enantiospecific allylboration of imines,k etimines,a nd indoles with enantioenriched g,g-disubstituted allylboronates. This method is impressive in its ability to provide amines with adjacent quaternary stereocenters in as tereodivergent manner,y et it proceeds through chirality transfer and requires enantioenriched precursors.M erging the merits of these two methods into am anifold wherein achiral g,gdisubstituted allylboronates undergo allylboration with imines in ac atalytic asymmetric fashion would be highly desirable.I no ur quest to fill this niche,w et hought that the allylboration of indole would be af ertile proving ground. Allylborations at the C2 position of indole have been reported by the groups of Aggarwal,[5g] Batey, [6] Bubnov, [7] and our group.[4c] Af ormidable challenge is to realize these reactions by asymmetric catalysis.In our previous studies, [4c] we found that ah ighly diastereoselective allylboration of indole could be achieved under mild conditions using a g,g-disubstituted geranylboronic acid, thus forming an indoline bearing an exocyclic quaternary stereocenter.C hong [5b] and Wu have reported on the asymmetric allylboration of cyclic imines using BINOL modified allylboronates whereas the Schaus group [8] described t...

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Regio‐ and Stereoselective Allylation and Crotylation of Indoles at C2 Through the Use of Potassium Organotrifluoroborate Salts

Cited by 63 publications

References 44 publications

Intramolecular Aminocyanation of Alkenes by NCN Bond Cleavage

Intramolecular Aminocyanation of Alkenes by NCN Bond Cleavage

Regioselective N-allylation and N-cinnamylation of indoles using CuI-exchanged hierarchical nanoporous material

Catalytic Asymmetric Allylboration of Indoles and Dihydroisoquinolines with Allylboronic Acids: Stereodivergent Synthesis of up to Three Contiguous Stereocenters

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