(Thio)Amidoindoles and (Thio)Amidobenzimidazoles: An Investigation of Their Hydrogen‐Bonding and Organocatalytic Properties in the Ring‐Opening Polymerization of Lactide
- 1 April 2010
- journal article
- research article
- Published by Wiley in Chemistry – A European Journal
- Vol. 16 (14), 4196-4205
- https://doi.org/10.1002/chem.200902912
Abstract
The mechanism of the ring-opening polymerization (ROP) of lactide catalyzed by two partner hydrogen-bonding organocatalysts was explored. New amidoindoles 4 a,c, thioamidoindoles 4 b,d, amidobenzimidazoles 5 a,c, and thioamidobenzimidazoles 5 b,c were synthesized and used as activators of the monomer. In the solid state and in solution, compounds 4 and 5 showed a propensity for self-association, which was evaluated. (Thio)Amides 4 and 5 do catalyze the ROP of lactide in the presence of a cocatalyst, tertiary amine 3 a or 3 b, which activates the growing polymer chain through hydrogen-bonding. Reactions were conducted in 2–24 h at 20 °C; conversion yields ranged between 22 and 100 %. A detailed study of the intermolecular interactions undertaken between the participating species showed that, as expected, simultaneous weak hydrogen bonds do exist to activate the reagents. Moreover, interactions have been revealed between the partner catalysts 4/5+3. ROP catalyzed by these partner activators is thus governed by multiple dynamic equilibria. The latter should be judiciously adjusted to fine-tune the catalytic properties of (thio)amides and organocatalysts, more generally.Keywords
This publication has 65 references indexed in Scilit:
- A Hydrosoluble Triphenylene That Preferentially Binds Acetylcholine, Epibatidine, and NicotineThe Journal of Organic Chemistry, 2009
- Bicyclic Guanidinium Tetraphenylborate: A Photobase Generator and A Photocatalyst for Living Anionic Ring-Opening Polymerization and Cross-Linking of Polymeric Materials Containing Ester and Hydroxy GroupsJournal of the American Chemical Society, 2008
- Organo-Catalyzed ROP of ϵ-Caprolactone: Methanesulfonic Acid Competes with Trifluoromethanesulfonic AcidMacromolecules, 2008
- A simple benzimidazole-based receptor for barbiturate and urea neutral guests that functions in polar solvent mixturesNew Journal of Chemistry, 2007
- Phosphazene Bases: A New Category of Organocatalysts for the Living Ring-Opening Polymerization of Cyclic EstersMacromolecules, 2007
- Organocatalytic Ring Opening Polymerization of Trimethylene CarbonateBiomacromolecules, 2006
- Enantioselective Michael Addition to α,β-Unsaturated Imides Catalyzed by a Bifunctional OrganocatalystAngewandte Chemie, 2005
- Thioxylation as One-Atom-Substitution Generates a Photoswitchable Element within the Peptide BackboneAngewandte Chemie-International Edition, 2000
- β-Thiopeptides: Synthesis, NMR Solution Structure, CD Spectra, and PhotochemistryHelvetica Chimica Acta, 1999
- Sulfonate Salts of Substituted Benzimidazoles1Journal of the American Chemical Society, 1947