Isothiourea-catalysed enantioselective pyrrolizine synthesis: synthetic and computational studies

Stark, Daniel G.; Williamson, Patrick; Gayner, Emma R; Musolino, Stefania F.; Kerr, Ryan W. F.; Taylor, James E.; Slawin, Alexandra M. Z.; O’Riordan, Timothy; Macgregor, Stuart A.; Smith, Andrew D.

doi:10.1039/c6ob01557c

Cited by 25 publications

(9 citation statements)

References 74 publications

(32 reference statements)

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“…In situ methanolysis cleaved the lactone to provide disubstituted pyrrolizines 59 in good yields and excellent stereoselectivities (Scheme 24). [ 31 ]…”

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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“…In situ methanolysis cleaved the lactone to provide disubstituted pyrrolizines 59 in good yields and excellent stereoselectivities (Scheme 24). [ 31 ]…”

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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“…1b ). 10 In this manuscript the application of this methodology for the preparation of 6-membered heterocycles is reported for the first time, allowing the synthesis of cis -chromenones 11 in up to 99 : 1 dr and 98 : 2 er ( Fig. 1c ).…”

mentioning

confidence: 92%

6-exo-trig Michael addition-lactonizations for catalytic enantioselective chromenone synthesis

et al. 2017

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“…This intramolecular protocol was extended to the catalytic enantioselective synthesis of pyrrolizines (Scheme 4). [23] Using commercially available catalyst ( R )‐BTM 9 (5 mol %), a range of pyrrole‐derived enone‐acids 8 were converted to dihydropyranones 10 . Following in situ ring‐opening with suitable amine and alcohol nucleophiles, the more stable pyrrolizine carboxylate derivatives 11 could be obtained in good to high yields (53–99 %) with excellent diastereo‐ and enantioselectivity (all ≥94:6 dr, ≥98:2 er).…”

Section: Catalyst Turnover Via Lactonisation/lactamisationmentioning

confidence: 99%

Generation and Reactivity of C(1)‐Ammonium Enolates by Using Isothiourea Catalysis

McLaughlin

Smith

2020

Chemistry A European J

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C(1)‐Ammonium enolates are powerful, catalytically generated synthetic intermediates applied in the enantioselective α‐functionalisation of carboxylic acid derivatives. This minireview describes the recent developments in the generation and application of C(1)‐ammonium enolates from various precursors (carboxylic acids, anhydrides, acyl imidazoles, aryl esters, α‐diazoketones, alkyl halides) using isothiourea Lewis base organocatalysts. Their synthetic utility in intra‐ and intermolecular enantioselective C−C and C−X bond forming processes on reaction with various electrophiles will be showcased utilising two distinct catalyst turnover approaches.

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Isothiourea-catalysed enantioselective pyrrolizine synthesis: synthetic and computational studies

Abstract: The isothiourea-catalysed enantioselective synthesis of cis-pyrrolizines is explored synthetically and computationally.

Cited by 25 publications

References 74 publications

Synthesis of Heterocycles by isothiourea organocatalysis

Synthesis of Heterocycles by isothiourea organocatalysis

6-exo-trig Michael addition-lactonizations for catalytic enantioselective chromenone synthesis

Generation and Reactivity of C(1)‐Ammonium Enolates by Using Isothiourea Catalysis

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