Abstract
Both E- and Z-N′-alkenyl urea derivatives of imidazolidinones may be formed selectively from enantiopure α-amino acids. Generation of their enolate derivatives in the presence of K + and [18]crown-6 induces intramolecular migration of the alkenyl group from N′ to Cα with retention of double bond geometry. DFT calculations indicate a partially concerted substitution mechanism. Hydrolysis of the enantiopure products under acid conditions reveals quaternary α-alkenyl amino acids with stereodivergent control of both absolute configuration and double bond geometry.
| Original language | English |
|---|---|
| Pages (from-to) | 2418-2422 |
| Number of pages | 5 |
| Journal | Angewandte Chemie - International Edition |
| Volume | 58 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - 18 Feb 2019 |
Bibliographical note
Funding Information:This work was supported by the ERC and EPSRC, the EPSRC Centre for Doctoral Training in Catalysis (EP/L016443/1), Syngenta (CASE award to JM-R) and the Presidential Leadership Program of Egypt (scholarship to MMA).
Funding Information:
We used standard DFT calculations (see Supporting Information for full computational details) to probe the mechanism of reaction of E and Z-3a, as set out [for (E,2S)-3a] in Scheme 5. After deprotonation, the charge on the enolate oxygen is stabilized by coordination to [K+[18]c-6] to give E-1. Development of the energetically accessible syn-carbometallation intermediate E-2 is supported by chelation of the [K+[18]c-6] counterion. A transition state E-TS could
Publisher Copyright:
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Funding
This work was supported by the ERC and EPSRC, the EPSRC Centre for Doctoral Training in Catalysis (EP/L016443/1), Syngenta (CASE award to JM-R) and the Presidential Leadership Program of Egypt (scholarship to MMA). We used standard DFT calculations (see Supporting Information for full computational details) to probe the mechanism of reaction of E and Z-3a, as set out [for (E,2S)-3a] in Scheme 5. After deprotonation, the charge on the enolate oxygen is stabilized by coordination to [K+[18]c-6] to give E-1. Development of the energetically accessible syn-carbometallation intermediate E-2 is supported by chelation of the [K+[18]c-6] counterion. A transition state E-TS could
Keywords
- DFT calculations
- quaternary amino acids
- rearrangement
- stereodivergence
- α-alkenylation
ASJC Scopus subject areas
- Catalysis
- General Chemistry