Double Bond Isomerization/Enantioselective Aza-Petasis−Ferrier Rearrangement Sequence as an Efficient Entry to Anti- and Enantioenriched β-Amino Aldehydes

Terada, Masahiro; Toda, Yasunori

doi:10.1021/ja902202g

Cited by 140 publications

(58 citation statements)

References 15 publications

(7 reference statements)

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“…However, whether the reaction benefits from large proximal sterics or small depends on the sterics of the nucleophile. For smaller displaced nucleophiles, large proximal sterics are advantageous, disfavouring Type I E pathways 29, 33, 35, 36, 37, 38, 72, 73, 74, 75, 76, 77, 78. However, if the nucleophile is large, small proximal sterics are essential 32, 34, 39, 79, 80.…”

Section: Resultsmentioning

confidence: 99%

Selecting Chiral BINOL‐Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

Reid

Goodman

2017

Chemistry A European J

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Choosing the optimal catalyst for a new transformation is challenging because the ideal molecular requirements of the catalyst for one reaction do not always simply translate to another. Large groups at the 3,3′ positions of the binaphthol rings are important for efficient stereoinduction but if they are too large this can lead to unusual or poor results. By applying a quantitative steric assessment of the substituents at the 3,3′ positions of the binaphthol ring, we have systematically studied the effect of modulating this group on enantioselectivity for a wide range of reactions involving imines, and verified this analysis using ONIOM calculations. We have shown that in most reactions, the stereochemical outcome depends on both proximal and remote sterics. Summarising detailed calculations into a simple qualitative model identifies and explains the steric features required for high selectivity. This model is consistent with seventy seven papers reporting reactions (over 1000 transformations in total), and provides a straightforward decision tree for selecting the best catalyst.

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Section: Resultsmentioning

confidence: 99%

Selecting Chiral BINOL‐Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

Reid

Goodman

2017

Chemistry A European J

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“…19 The isomerization step was catalyzed by a combination of nickel(II) complex and LiBHEt 3 , and after an aqueous work-up and filtration through SiO 2 , phosphoric acid 6 was added to catalyze the azaPetasiseFerrier step. Z-Configuration of the hemiaminal vinyl ether leads to 1,2-anti-product, and E correspondingly to synproduct, albeit in slightly lower selectivities.…”

Section: No-acetalsmentioning

confidence: 99%

Imine and iminium precursors as versatile intermediates in enantioselective organocatalysis

Kataja

Masson

2014

Tetrahedron

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“…The binary organo/metal catalyst systems disclosed so far include the combination of transition-metal complexes based on Pd, [6,7] Au, [8] Rh, [9, 10] Ru, [11,12] and other transition metals [13,14] with chiral organocatalysts. In contrast, combinations of Lewis acids and phosphoric acids have rarely found application in asymmetric relay catalysis.…”

mentioning

confidence: 99%

“…Recently, the combined use of organocatalysts and metal complexes in relay and cooperative catalysis has led to the creation of new enantioselective protocols. [5][6][7][8][9][10][11][12][13][14] More significantly, asymmetric relay catalysis (ARC) has been proven to enable the discovery of unprecedented stepeconomical transformations. [5] Successful relay catalysis relies on the compatibility and more importantly, on the synergism of metal complexes and organocatalysts.…”

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confidence: 99%

Step‐Economical Synthesis of Tetrahydroquinolines by Asymmetric Relay Catalytic Friedländer Condensation/Transfer Hydrogenation

et al. 2011

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Chiral 1,2,3,4-tetrahydroquinoline derivatives have found widespread application in the preparation of naturally occurring alkaloids and pharmaceutically relevant molecules. [1] Their great synthetic importance has stimulated a boom in the development of asymmetric synthetic methods. [2, 3] The most common access to this structural motif is the asymmetric reduction of quinolines.[3] Although it is straightforward, this approach requires preformed quinoline derivatives and thereby suffers from moderate step economy. The direct and enantioselective conversion of readily available precursors of quinolines into the 1,2,3,4-tetrahydroquinolines would provide a more elegant approach, but such methods remain extremely rare. Herein we describe a new relay catalytic reaction to produce 1,2,3,4-tetrahydroquinolines in high levels of enantiopurity by using easily accessible 2-aminobenzaldehydes and enolizable carbonyl-containing compounds as reagents.Step economy is a preeminent concept in contemporary organic synthesis.[4] It has been accepted as an ultimate goal to construct pharmaceutical compounds and complex natural products. Recently, the combined use of organocatalysts and metal complexes in relay and cooperative catalysis has led to the creation of new enantioselective protocols.[5-14] More significantly, asymmetric relay catalysis (ARC) has been proven to enable the discovery of unprecedented stepeconomical transformations.[5] Successful relay catalysis relies on the compatibility and more importantly, on the synergism of metal complexes and organocatalysts. The binary organo/metal catalyst systems disclosed so far include the combination of transition-metal complexes based on Pd, [6,7] Au, [8] Rh, [9, 10] Ru, [11,12] and other transition metals [13,14] with chiral organocatalysts. In contrast, combinations of Lewis acids and phosphoric acids have rarely found application in asymmetric relay catalysis.[15]The Friedländer condensation has long been recognized as a reliable and preparatively straightforward route to quinolines.[16] Either Brønsted or Lewis acids are able to efficiently promote this transformation. On the other hand, chiral phosphoric acids [17] have been excellent catalysts for the asymmetric transfer hydrogenation of quinolines with Hantzsch esters. [3a, 18] Encouraged by these elegant achievements, we proposed a sequence consisting of a Friedländer condensation and transfer hydrogenation catalyzed by a combination of an achiral Lewis acid and a chiral Brønsted acid for the direct conversion of 2-aminobenzaldehydes and enolizable compounds containing carbonyl groups into highly optically active 1,2,3,4-tetrahydroquinoline derivatives (Scheme 1).Our initial study began with the reaction of 2-aminobenzaldehyde (1 a) and ethyl acetoacetate (2 a) with Hantzsch ester 3 a catalyzed by phosphoric acid 5 a (10 mol %) in toluene at 35 8C. Encouragingly, the reaction proceeded with high diastereoselectivity in favor of the anti diastereomer and with 90 % ee for the major product; however, the yield was...

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Double Bond Isomerization/Enantioselective Aza-Petasis−Ferrier Rearrangement Sequence as an Efficient Entry to Anti- and Enantioenriched β-Amino Aldehydes

Cited by 140 publications

References 15 publications

Selecting Chiral BINOL‐Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

Selecting Chiral BINOL‐Derived Phosphoric Acid Catalysts: General Model To Identify Steric Features Essential for Enantioselectivity

Imine and iminium precursors as versatile intermediates in enantioselective organocatalysis

Step‐Economical Synthesis of Tetrahydroquinolines by Asymmetric Relay Catalytic Friedländer Condensation/Transfer Hydrogenation

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