A practical synthesis of optically active arylglycines via catalytic asymmetric Strecker reaction

Banphavichit, Vorawit; Mansawat, Woraluk; Bhanthumnavin, Worawan; Vilaivan, Tirayut

doi:10.1016/j.tet.2009.04.098

Cited by 23 publications

(8 citation statements)

References 49 publications

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“…Vilaivan and co-workers demonstrated that titanium complexes with tridentate N -salicyl-β-aminoalcohols acted as effective catalysts for enantioselective Strecker reaction of aromatic aldimines (Scheme ). The configuration as well as the bulkiness of the β-substituent significantly influenced the enantioselectivity. Use of the most efficient ligand, ( S )- N -(2-hydroxybenzyl)alaninol, allowed the reaction to proceed, affording the α-arylaminonitriles in >98% ee in the best cases.…”

Section: Nucleophilic Cyanation Of Carbonyl Compounds and Iminesmentioning

confidence: 99%

Catalytic Asymmetric Cyanation Reactions

2016

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Catalytic asymmetric cyanations of prochiral unsaturated compounds affording the corresponding nitrile products in high enantiomeric excess (≥90% in general) are summarized in this review. The nucleophilic cyanide addition onto aldehydes, ketones, and imines is promoted by chiral metal complexes and organocatalysts. Recent progress in asymmetric conjugate cyanation of α,β-unsaturated carbonyl compounds is also discussed. The asymmetric cyanation of unactivated alkenes is catalyzed by chiral transition-metal complexes. Current topics of intramolecular carbocyanation and aminocyanation in addition to the traditional hydrocyanation are reviewed.

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Section: Nucleophilic Cyanation Of Carbonyl Compounds and Iminesmentioning

confidence: 99%

Catalytic Asymmetric Cyanation Reactions

2016

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“…The amino nitriles 3a-g were hydrolyzed to the corresponding amino acids 4a-g and the configurations were assigned in comparison with their reported specific rotation values. [16] To illustrate the applicability and reproducibility of the present methodology, the cyanation of one gram each of imines 2f and 2g was carried out and further converted [17] to the corresponding amino acids 4f and 4g (Scheme 3). The amino acids 4f and 4g are chiral intermediates that can be potentially used for the synthesis of (3S)-4-benzyl-3-(4-fluorophenyl)morpholin-2-one [18] and amoxicillin, [19] respectively.…”

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confidence: 99%

A Remarkable Titanium‐Catalyzed Asymmetric Strecker Reaction using Hydrogen Cyanide at Room Temperature

Balamurugan

Seayad

et al. 2010

Adv Synth Catal

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Close to perfect enantioselectivity (up to 98% ee) is obtained for the formation of amino nitriles using hydrogen cyanide (HCN) as the cyanide source at room temperature for the first time. In an operationally simple process, the catalyst generated from a partially hydrolyzed titanium alkoxide (PHTA) and (S)-N-salicyl-b-amino alcohol ligand, catalyzes the cyanation of imines in a short reaction time.Keywords: enantioselective cyanation; hydrogen cyanide; imines; in-situ IR studies; Strecker reaction; titanium catalystThe enantioselective addition of carboxyl group or its equivalent onto imines constitutes an elegant method for the synthesis of a-amino acids.[1] The most important example of this strategy is the Strecker reaction [2] or the cyanation of preformed imines followed by hydrolysis. After the first catalytic enantioselective cyanation of imines in 1996 by Lipton and co-workers using a chiral diketopiperazine as an organo catalyst, [3] significant progress has been made [4] in the design of both organic [5][6][7] and metal [8][9][10][11] catalysts achieving very high enantioselectivities. The main drawbacks of most of these methodologies are the requirement of very low temperatures (À75 to À40 8C) and the use of expensive TMSCN as the cyanide source which may preclude the use of Strecker reaction on the large-scale synthesis of chiral amino acids. Although high enantioselectivities (up to 98% ee) were recently reported at temperatures 0-23 8C using TMSCN as the cyanide source, [11] achieving higher enantioselectivities using cheaper cyanide sources such as HCN at these temperatures remains a challenge. To the best of our knowledge, higher enantioselectivities (> 90% ee) have not been reported at temperatures higher than À75 8C using HCN [12] as the cyanide source with organic [5] or metal catalysts. [8] This may be mainly due to the competing non-catalytic racemic reaction pathway with HCN at these temperatures. Herein, we report the first enantioselective cyanation of imines at room temperature using HCN as a primary cyanide source.In a recent report, [11d] we disclosed the use of a partially hydrolyzed titanium alkoxide (PHTA) [13] together with the chiral ligand (S)-2-[(1-hydroxy-3,3-dimethylbutan-2-ylamino)methyl]phenol (1) as an efficient catalyst system (Scheme 1) for the enantioselective cyanation of imines using TMSCN as the cyanide source and n-BuOH as the proton donor giving up to 98% ee at room temperature. Attempts to use HCN [14,15] as the cyanide source instead of TMSCN at room temperature resulted only in the formation of racemic product 3a (Table 1, entry 1). Gratifyingly, when 1 equivalent of HCN was used in combination with 1.5 equivalents of TMSCN, 78% ee was observed with complete conversion in 1 h (Table 1, entry 2). Scheme 1. Preparation of chiral catalyst for cyanation reactions.

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“…49 The Nbenzhydryl α-arylaminonitrile intermediates were prepared in excellent yield (89-99%) and enantiomeric purity (96 to >98% ee) by enantioselective cyanation of aldimines with TMSCN/iPrOH in the presence of 2.5 mol % of an easily prepared Ti/chiral amino alcohol complex at 0 ºC, without requiring slow addition of the cyanating agent. The easily racemized α-aminonitrile intermediates were efficiently hydrolyzed by an aqueous HCl/TFA mixture to give the arylglycine derivatives in good yield (60-92%) and moderate to excellent enantiomeric purity (85-98% ee …”

Section: Scheme 19mentioning

confidence: 99%

Recent advances on asymmetric Strecker reactions

Cai¹,

Xie²

2014

Arkivoc

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The Strecker reaction is one of the most attractive methods for the synthesis of α-amino acids and other bioactive compounds including natural products. The asymmetric Strecker reaction represents a simple and efficient method for the synthesis of optically pure α-amino acid derivatives, nucleic acids, various nitrogen and sulfur containing heterocycles and pharmaceuticals. Over the past several decades, considerable effort has been devoted towards the development of asymmetric Strecker reactions. This review provides an overview of recent asymmetric Strecker reactions, from diastereoselective reactions and catalytic enantioselective reactions including chiral catalytic metal systems and chiral organocatalytic systems.

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A practical synthesis of optically active arylglycines via catalytic asymmetric Strecker reaction

Cited by 23 publications

References 49 publications

Catalytic Asymmetric Cyanation Reactions

Catalytic Asymmetric Cyanation Reactions

A Remarkable Titanium‐Catalyzed Asymmetric Strecker Reaction using Hydrogen Cyanide at Room Temperature

Recent advances on asymmetric Strecker reactions

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