Organocatalytic Michael addition–lactonisation of carboxylic acids using α,β-unsaturated trichloromethyl ketones as α,β-unsaturated ester equivalents

Morrill, Louis C.; Stark, Daniel G.; Taylor, James E.; Smith, S.M.; Squires, James A.; D’Hollander, Agathe C. A.; Simal, Carmen; Shapland, Peter; O’Riordan, Timothy; Smith, Andrew D.

doi:10.1039/c4ob01788a

Cited by 40 publications

(20 citation statements)

References 52 publications

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“…In this case HyperBTM ( 9 ) was employed to activate several arylacetic acids to give trans lactones with excellent levels of selectivity (Scheme ). The same group demonstrated that a similar intermolecular process was also possible with trifluoromethylenones, trichloromethylenones and α‐ketophosphonates …”

Section: Itu‐catalyzed Reactions Involving Chiral Acylisothiouronimentioning

confidence: 88%

Enantioselective Catalysis by Chiral Isothioureas

et al. 2016

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International audienceThis review covers recent developments relating to organocatalyzed transformations by chiral isothioureas (ITUs) since their original introduction by Birman in 2006. This class of nucleophilic heterocycles was first involved in anhydride activation in enantioselective acyl transfer reactions, but it was more recently shown that activation of other reagents was possible, considerably enlarging their number of catalytic enantioselective transformations. Four main modes of activation as Lewis bases can currently be listed: (1) acylisothiouronium intermediates involved in acyl transfer, (2) silylisothiouronium species involved in silyl transfer, (3) acylisothiouronium enolates involved in several concerted and formal pericyclic transformations, and (4) α,_-unsaturated acylisothiouronium species involved in domino transformations. This review is organized according to these different modes of activation of chiral isothioureas

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Section: Itu‐catalyzed Reactions Involving Chiral Acylisothiouronimentioning

confidence: 88%

Enantioselective Catalysis by Chiral Isothioureas

et al. 2016

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“…Notably,t he 2substitution pattern frequently provides reduced stereoselectivity in related isothiourea-catalyzed methods. [30] b 2 -Amino esters 24 and 25 with 1-and 2-naphthyl substituents were readily prepared, as was heteroaromatic 2-thienyl 26.Beyond aryl acetic acid derivatives,t he use of (E)-pent-3-enoic acid pentafluorophenyl ester was also productive,p roviding 3alkenyl-substituted b 2 -amino ester 27 in excellent er. The consistent yield and enantiocontrol observed with variation in both steric and electronic aryl substitution within the ester component indicate that neither provide as ignificant bias in this process.F urther investigations probed the effect of Nsubstituents within the hemiaminal ether reaction partner (Table 2B).…”

Section: Scope Limitations and Synthetic Applicationsmentioning

confidence: 99%

Enantioselective Synthesis of α‐Aryl‐β²‐Amino‐Esters by Cooperative Isothiourea and Brønsted Acid Catalysis

et al. 2021

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The synthesis of α‐aryl‐β2‐amino esters through enantioselective aminomethylation of an arylacetic acid ester in high yields and enantioselectivity via cooperative isothiourea and Brønsted acid catalysis is demonstrated. The scope and limitations of this process are explored (25 examples, up to 94 % yield and 96:4 er), with applications to the synthesis of (S)‐Venlafaxine⋅HCl and (S)‐Nakinadine B. Mechanistic studies are consistent with a C(1)‐ammonium enolate pathway being followed rather than an alternative dynamic kinetic resolution process. Control studies indicate that (i) a linear effect between catalyst and product er is observed; (ii) an acyl ammonium ion can be used as a precatalyst; (iii) reversible isothiourea addition to an in situ generated iminium ion leads to an off‐cycle intermediate that can be used as a productive precatalyst.

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“…The enolate was also utilized in intermolecular Michael‐addition‐catalyst elimination cascade sequence in combination with different types of suitable Michael acceptors in course of preparing several cyclic molecules like substituted δ ‐lactones and lactams (Scheme 30). [ 35,36 ]…”

Section: Six Membered Heterocycle Formation By Formal and Concerted [mentioning

confidence: 99%

Synthesis of Heterocycles by isothiourea organocatalysis

Biswas¹,

Mondal

Maji

2020

Journal of Heterocyclic Chem

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Isothiourea was first employed as catalyst by Birman in 2006 for the enantioselective acyl transfer reaction. The catalyst was then well explored in the course of kinetic resolution and desymmetrization studies. A few years later, Romo and Smith applied isothiourea catalysis in enantioselective cascade reactions to prepare carbocycles and heterocycles acessing new reactivities of isothiourea. Several research groups were then attracted toward this new field of organocatalysis, and applied isothioureas as nucleophilic catalysts in executing cascade methodologies to synthesize various intresteting molecular scaffolds including heterocycles. The present review documents a summary on the construction of heterocyclic molecules by isothiourea organocatalysis. Heterocycles are of prime interest to organic chemists due to their omnipresence in natural products and bioactive molecules. The Lewis basic nucleophilic catalyst isothioureas play a pivotal role in the cascades to generate either α,β‐unsaturated acyl isothiouronium ion or isothiouronium enolate as the prime reaction intermediate. We have covered the reactions involving two intermediates of opposite reactivities affording various heterocycles.

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Organocatalytic Michael addition–lactonisation of carboxylic acids using α,β-unsaturated trichloromethyl ketones as α,β-unsaturated ester equivalents

Cited by 40 publications

References 52 publications

Enantioselective Catalysis by Chiral Isothioureas

Enantioselective Catalysis by Chiral Isothioureas

Enantioselective Synthesis of α‐Aryl‐β²‐Amino‐Esters by Cooperative Isothiourea and Brønsted Acid Catalysis

Synthesis of Heterocycles by isothiourea organocatalysis

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Organocatalytic Michael addition–lactonisation of carboxylic acids using α,β-unsaturated trichloromethyl ketones as α,β-unsaturated ester equivalents

Cited by 40 publications

References 52 publications

Enantioselective Catalysis by Chiral Isothioureas

Enantioselective Catalysis by Chiral Isothioureas

Enantioselective Synthesis of α‐Aryl‐β2‐Amino‐Esters by Cooperative Isothiourea and Brønsted Acid Catalysis

Synthesis of Heterocycles by isothiourea organocatalysis

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Enantioselective Synthesis of α‐Aryl‐β²‐Amino‐Esters by Cooperative Isothiourea and Brønsted Acid Catalysis