Aqueous Asymmetric Mukaiyama Aldol Reaction Catalyzed by Chiral Gallium Lewis Acid with Trost‐Type Semi‐Crown Ligands

Li, Hui‐Jing; Tian, Hongyu; Wu, Yan‐Chao; Chen, Yongjun; Liu, Li; Wang, Dong; Li, Chao‐Jun

doi:10.1002/adsc.200505089

Cited by 64 publications

(25 citation statements)

References 37 publications

(16 reference statements)

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“…Consequently, the Lewis-acidic and water-tolerant features of lanthanide(III) salts have aroused much interest in aqueous lanthanide-catalyzed bond-forming reactions [ 1 , 2 , 3 , 4 , 5 , 6 ]. We are studying the Mukaiyama aldol reaction between a silyl enol ether and an aldehyde because this reaction can be both water-tolerant and stereoselective, making it an important carbon–carbon bond-forming reaction ( Figure 1 ) [ 3 , 4 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

The Role of Water in Lanthanide-Catalyzed Carbon–Carbon Bond Formation

2012

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Section: Introductionmentioning

confidence: 99%

The Role of Water in Lanthanide-Catalyzed Carbon–Carbon Bond Formation

2012

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“…In 2002, Ga(OTf) 3 with chiral Trost‐type semicrown ligand 39 115 was discovered to be an efficient catalyst for asymmetric Mukaiyama aldol reactions in aqueous media (Scheme ) 116. UV‐vis titration and ESI‐MS analysis confirmed this gallium complex to be a 1:1 complex 117. Control experiments performed without the ligand suggested that it played a key role in accelerating the reaction and suppressing the hydrolysis of the silicon enolates.…”

Section: Asymmetric Catalysts In Aqueous Media and Watermentioning

confidence: 84%

A Photocleavable Auxiliary for Extended Native Chemical Ligation

Nadler

Hansen

et al. 2015

Eur J Org Chem

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To extend the scope of native chemical ligations beyond X‐Cys connections, auxiliaries that contain thiol moieties were developed to mimic the function of the Cys residue in the ligation reaction/capture step. Auxiliaries known so far feature complicated attachment protocols and generally need harsh conditions for their cleavage. Herein, we present the development of a new photoremovable ligation auxiliary, which is easily synthesized and attached to peptides that contain a variety of N‐terminal amino acids by a reductive amination reaction. Ligations at Gly‐Gly and Ala‐Gly junctions were carried out with high conversion, and the auxiliary can be cleaved from the final product by using a mild photolysis protocol. This methodological advancement is an important step forward in peptide ligation chemistry.

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“…In 2002, Ga(OTf) 3 with chiral Trost‐type semi‐crown ligand L8 [ 35] was reported as an efficient catalyst for asymmetric Mukaiyama aldol reactions in aqueous media . The substrate scope was relatively wide and included thioketene silyl acetals, although the use of aliphatic aldehydes led to a significant loss of enantioselectivity . Chiral catalysts formed with Zn(OTf) 2 and i Pr‐pybox ligand L9 or FeCl 2 and hydroxymethyl‐pybox ligand L10 were also reported for asymmetric Mukaiyama aldol reactions in aqueous media.…”

Section: Highlightsmentioning

confidence: 99%

Development of Chiral Catalysts for Mukaiyama Aldol Reactions in Aqueous Media

Kitanosono

Kobayashi

2014

The Chemical Record

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Since the discovery of the Mukaiyama aldol reaction in 1973, tremendous efforts have been made to develop a definitive catalyst that catalyzes asymmetric Mukaiyama aldol reactions under mild conditions with broad substrate tolerance. Forty years later, an exhaustive search for a water-compatible Lewis acid was able to uncover the hidden potential of iron(II) and bismuth(III), leading to the establishment of broadly applicable and versatile catalytic systems for asymmetric Mukaiyama aldol reactions in aqueous media. The ternary catalytic system was able to expand the substrate generality considerably as the most distinguished catalyst ever reported. The superiority of this methodology over conventional methods has also been demonstrated in terms of high catalytic activity, simplicity of experimental procedures, and a wide substrate range including aqueous aldehydes, for which the stereochemistry had been regarded as difficult to control. Furthermore, a facile synthesis of the chiral ligand underscores its versatility. The reaction did not proceed at all without use of water. In the postulated mechanism, water plays prominent roles in: (1) producing the active metal complexes with a high water-exchange rate constant (3.2 × 10(6)) to activate substrates effectively and to catalyze the reaction through a rapid proton transfer on the order of picoseconds; (2) facilitating the catalytic turnover with simultaneous desilylation as direct access to aldol adducts or facile recovery of active metal complexes; and (3) stabilizing rigid transition states composed of metal complexes and reactants through entropy-driven aggregation derived from the highest cohesive energy density.

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Aqueous Asymmetric Mukaiyama Aldol Reaction Catalyzed by Chiral Gallium Lewis Acid with Trost‐Type Semi‐Crown Ligands

Cited by 64 publications

References 37 publications

The Role of Water in Lanthanide-Catalyzed Carbon–Carbon Bond Formation

The Role of Water in Lanthanide-Catalyzed Carbon–Carbon Bond Formation

A Photocleavable Auxiliary for Extended Native Chemical Ligation

Development of Chiral Catalysts for Mukaiyama Aldol Reactions in Aqueous Media

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