The Design of Novel, Synthetically Useful (Thio)urea-Based Organocatalysts

Connon, Stephen J.

doi:10.1055/s-0028-1087557

Cited by 65 publications

(61 citation statements)

References 25 publications

(35 reference statements)

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“…When aD KR is performed in as tirred tank reactor, only one of the two component reactions can be optimized and the common optimum is obviously suboptimal for both of them. [52][53][54][55][56][57][58][59][60][61][62][63][64] This could be solved if the two component reactions of DKR are separated in space.…”

Section: Introductionmentioning

confidence: 99%

A Continuous‐Flow Cascade Reactor System for Subtilisin A‐ Catalyzed Dynamic Kinetic Resolution of N‐tert‐Butyloxycarbonylphenylalanine Ethyl Thioester with Benzylamine

et al. 2016

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Alcalase (Subtilisin A) was immobilized by simple hydrophobic adsorption onto various surface-grafted macroporous silicag els resulting in easy-to-prepare and stable biocatalystse nabling the efficient kinetic resolution (KR) and dynamic kinetic resolution (DKR)o fr acemic N-Boc-phenylalanine ethyl thioester with benzylamine.T he immobilized Alcalaseb iocatalysts, which retained their activity and selectivity when stored at 4 8 8Cf or more than ay ear, were testedi ne nzymatic aminolysis in batch and continuous-flow KRs resulting in (S)-N-Bocphenylalanine benzylamide in high enantiomeric purity. In KR of the racemict hioester by Alcalasecatalyzed aminolysis in ac ontinuous-flow reactor, the productivity (specific reactionr ate, r flow )a nd enantiomeric ratio (E)w ere studied in the 0-100 8 8C range.T he effect of the temperature on base-catalyzed racemization of the non-transformed (R)-thioester in ac ontinuous-flow reactor was also investigated in the 0-150 8 8Cr ange.T he continuous-mode DKR of the racemic thioester in as erialc ascade systemo fsix biocatalyst-filled columns at 50 8 8Cf or KR and five grafteds ilica gel-filled columns at 150 8 8Cf or racemization resulted in the formation of the (S)-benzylamide in 79% conversion, 8.17 g L À1 h À1 volumetric productivity and 98% ee. This is the first example of ad ynamic kinetic resolution of an amino acid derivative in continuous-flow mode using an alternating cascade of packed-bed enzyme reactors and racemization reactors kept at different temperatures.

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Section: Introductionmentioning

confidence: 99%

A Continuous‐Flow Cascade Reactor System for Subtilisin A‐ Catalyzed Dynamic Kinetic Resolution of N‐tert‐Butyloxycarbonylphenylalanine Ethyl Thioester with Benzylamine

et al. 2016

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“…Recently, hydrogen-bond donors such as ureas/thioureas, [10][11][12][13][14][15][16][17][18][19][20][21][22][23] BINOL/diols, [24][25][26][27][28][29][30][31][32] and phosphoric acids [33][34][35][36][37][38][39][40] have been also recognized as efficient organocatalysts. Novel urea and thiourea derivatives were developed as organocatalysts and their potential as a general acid has been successfully demonstrated by several groups.…”

Section: Introductionmentioning

confidence: 99%

Development of Chiral Thiourea Catalysts and Its Application to Asymmetric Catalytic Reactions

2010

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We have developed several multifunctional thiourea catalysts bearing a tertiary amine or an 1,2-amino alcohol in expectation of their synchronous activation of a nucleophile and an electrophile through both acid-base and hydrogen-bonding interactions. From these studies, it was revealed that the weak acidity of thioureas compared with metallic Lewis acids could be overcome by this modification. The bifunctional aminothiourea could be used efficiently for a wide range of diastereoselective and enantioselective nucleophilic reactions such as Michael addition of 1,3-dicarbonyl compounds to nitroolefines, aza-Henry reaction of nitroalkanes to N-Boc imines, and hydrazination of cyclic b b-keto esters. We also discovered that multifunctional thiourea catalyst, bearing an 1,2-amino alcohol moiety, significantly accelerated the Petasis-type reaction of alkenylboronic acids to Nphenoxycarbonyl quinolinium salts, prepared from quinolines and phenyl chloroformate, to afford 1,2-addition products with high enantioselectivity (up to 97% ee). Furthermore, to expand the synthetic applicability of the thiourea-catalyzed asymmetric reactions, tandem organocatalyzed reactions were explored to establish the concise one-pot synthesis of chiral densely functionalized three-, five-, and six-membered compounds.

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“…[8][9][10] The most commonly used catalysts are derived from trans-cyclohexyldiamine, 2,2'-binaphthyl, amino acids, or the cinchona alkaloids. [11][12][13][14] Although carbohydrate are very attractive starting material because of their availability and well defined stereocenters, only few thiourea organocatalysts derived from saccharide were used in asymmetric organocatalytic reactions, mainly for Mannich and aza-Henry reactions. [15][16][17][18] As a part of our ongoing program devoted to asymmetric catalysis, we were interested in the development of new chiral ligands derived from dianhydrohexitols (isomannide, isosorbide and isoidide).…”

Section: Introductionmentioning

confidence: 99%

Dianhydrohexitols: new tools for organocatalysis. Application in enantioselective Friedel-Crafts alkylation of indoles with nitroalkenes

Chen¹,

Guillarme²,

Saluzzo³

2013

Arkivoc

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The Design of Novel, Synthetically Useful (Thio)urea-Based Organocatalysts

Abstract: Selected recent developments in the area of (thio)ureamediated organocatalysis from our laboratory are summarised.

Cited by 65 publications

References 25 publications

A Continuous‐Flow Cascade Reactor System for Subtilisin A‐ Catalyzed Dynamic Kinetic Resolution of N‐tert‐Butyloxycarbonylphenylalanine Ethyl Thioester with Benzylamine

A Continuous‐Flow Cascade Reactor System for Subtilisin A‐ Catalyzed Dynamic Kinetic Resolution of N‐tert‐Butyloxycarbonylphenylalanine Ethyl Thioester with Benzylamine

Development of Chiral Thiourea Catalysts and Its Application to Asymmetric Catalytic Reactions

Dianhydrohexitols: new tools for organocatalysis. Application in enantioselective Friedel-Crafts alkylation of indoles with nitroalkenes

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