Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower Temperatures
Room temperature ionic liquids (RTILs) have been widely used as (co)solvents in several catalytic processes modifying, in most of the cases, the catalyst activity and/or the selectivity for the studied reactions. However, there are just a few examples of their use in hydrogen bonding organocatalysis...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-01-01
|
| Series: | Molecules |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1420-3049/26/2/355 |
| _version_ | 1797412802946662400 |
|---|---|
| author | Fabricio R. Bisogno Rosario Fernández Jose María Lassaletta Gonzalo de Gonzalo |
| author_facet | Fabricio R. Bisogno Rosario Fernández Jose María Lassaletta Gonzalo de Gonzalo |
| author_sort | Fabricio R. Bisogno |
| collection | DOAJ |
| description | Room temperature ionic liquids (RTILs) have been widely used as (co)solvents in several catalytic processes modifying, in most of the cases, the catalyst activity and/or the selectivity for the studied reactions. However, there are just a few examples of their use in hydrogen bonding organocatalysis. In this paper, we show the positive effect of a set of imidazole-based ionic liquids ([bmim]BF<sub>4</sub> and [hmim]PF<sub>6</sub>) in the enantioselective addition of formaldehyde <i>tert</i>-butylhydrazone to prochiral α-keto esters catalyzed by a sugar-based chiral thiourea. Reactions performed in the presence of low percentages of RTILs led to an increase of the catalyst activity, thereby making possible to work at lower temperatures. Thus, the chiral <i>tert</i>-butyl azomethyl tertiary alcohols could be obtained with moderate to good conversions and higher enantioselectivities for most of the studied substrates when using up to 30 vol% of [hmim]PF<sub>6</sub> as a cosolvent in processes performed in toluene. |
| first_indexed | 2024-03-09T05:07:22Z |
| format | Article |
| id | doaj.art-d20cde2601af44c7be9a5061a5600924 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-09T05:07:22Z |
| publishDate | 2021-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-d20cde2601af44c7be9a5061a56009242023-12-03T12:53:19ZengMDPI AGMolecules1420-30492021-01-0126235510.3390/molecules26020355Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower TemperaturesFabricio R. Bisogno0Rosario Fernández1Jose María Lassaletta2Gonzalo de Gonzalo3Facultad de Ciencias Químicas, Instituto de Investigaciones en Físico-Química de Córdoba, Universidad Nacional de Córdoba, (INFIQC, CONICET-UNC), Haya de la Torre y Medina Allende, Ciudad Universitaria, Córdoba 5000, ArgentinaDepartamento de Química Orgánica, Universidad de Sevilla, c/Profesor García González 1, 41012 Sevilla, SpainInstituto de Investigaciones Químicas (CSIC-US) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Avda. Américo Vespucio 49, 41092 Sevilla, SpainDepartamento de Química Orgánica, Universidad de Sevilla, c/Profesor García González 1, 41012 Sevilla, SpainRoom temperature ionic liquids (RTILs) have been widely used as (co)solvents in several catalytic processes modifying, in most of the cases, the catalyst activity and/or the selectivity for the studied reactions. However, there are just a few examples of their use in hydrogen bonding organocatalysis. In this paper, we show the positive effect of a set of imidazole-based ionic liquids ([bmim]BF<sub>4</sub> and [hmim]PF<sub>6</sub>) in the enantioselective addition of formaldehyde <i>tert</i>-butylhydrazone to prochiral α-keto esters catalyzed by a sugar-based chiral thiourea. Reactions performed in the presence of low percentages of RTILs led to an increase of the catalyst activity, thereby making possible to work at lower temperatures. Thus, the chiral <i>tert</i>-butyl azomethyl tertiary alcohols could be obtained with moderate to good conversions and higher enantioselectivities for most of the studied substrates when using up to 30 vol% of [hmim]PF<sub>6</sub> as a cosolvent in processes performed in toluene.https://www.mdpi.com/1420-3049/26/2/355organocatalysisionic liquidsene-type reactionstertiary alcoholssolvent engineeringasymmetric catalysis |
| spellingShingle | Fabricio R. Bisogno Rosario Fernández Jose María Lassaletta Gonzalo de Gonzalo Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower Temperatures Molecules organocatalysis ionic liquids ene-type reactions tertiary alcohols solvent engineering asymmetric catalysis |
| title | Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower Temperatures |
| title_full | Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower Temperatures |
| title_fullStr | Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower Temperatures |
| title_full_unstemmed | Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower Temperatures |
| title_short | Room Temperature Ionic Liquids in Asymmetric Hetero-Ene Type Reactions: Improving Organocatalyst Performance at Lower Temperatures |
| title_sort | room temperature ionic liquids in asymmetric hetero ene type reactions improving organocatalyst performance at lower temperatures |
| topic | organocatalysis ionic liquids ene-type reactions tertiary alcohols solvent engineering asymmetric catalysis |
| url | https://www.mdpi.com/1420-3049/26/2/355 |
| work_keys_str_mv | AT fabriciorbisogno roomtemperatureionicliquidsinasymmetricheteroenetypereactionsimprovingorganocatalystperformanceatlowertemperatures AT rosariofernandez roomtemperatureionicliquidsinasymmetricheteroenetypereactionsimprovingorganocatalystperformanceatlowertemperatures AT josemarialassaletta roomtemperatureionicliquidsinasymmetricheteroenetypereactionsimprovingorganocatalystperformanceatlowertemperatures AT gonzalodegonzalo roomtemperatureionicliquidsinasymmetricheteroenetypereactionsimprovingorganocatalystperformanceatlowertemperatures |