Jan 09, 2024

Public workspaceSynthesis of 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2,4,6-(1H,3H,5H)-trione (CP8) V.2

DOI
dx.doi.org/10.17504/protocols.io.bp2l6xd71lqe/v2
  • 1Department of Chemistry/Pharmacology, University of Oxford, OX1 3PT, UK;
  • 2Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3PT, UK;
  • 3Oxford Parkinson’s Disease Centre, University of Oxford, Oxford, United Kingdom;
  • 4Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815
Cláudia C. Mendes
Open access
DOI: dx.doi.org/10.17504/protocols.io.bp2l6xd71lqe/v2
Protocol Citation: Carole JR Bataille, Katherine Brimblecombe, Stephanie J Cragg 2024. Synthesis of 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2,4,6-(1H,3H,5H)-trione (CP8). protocols.io https://dx.doi.org/10.17504/protocols.io.bp2l6xd71lqe/v2Version created by Cláudia C. Mendes
Manuscript citation:
Kang, S.; Cooper, G.; Dunne, S. F.; Dusel, B.; Luan, C.-H.; Surmeier, D. J.; Silverman, R. B. CaV1.3-selective L-type calcium channel antagonists as potential new therapeutics for Parkinson's disease. Nature Communications 2012, 3 (1), 1146. DOI: 10.1038/ncomms2149. 

Brimblecombe KR, Connor-Robson N, Bataille CJR, Roberts BM, Gracie C, O'Connor B, Te Water Naude R, Karthik G, Russell AJ, Wade-Martins R, Cragg SJ. Inhibition of striatal dopamine release by the L-type calcium channel inhibitor isradipine co-varies with risk factors for Parkinson's. Eur J Neurosci. 2023 Nov 8. doi: 10.1111/ejn.16180. Epub ahead of print. PMID: 37941514.
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License,  which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: December 20, 2023
Last Modified: January 09, 2024
Protocol Integer ID: 92555
Keywords: calcium channel antagonist, 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2, 4, 6-(1H, 3H, 5H)-trione (8), synthesis
Funders Acknowledgement:
Aligning Science Across Parkinson’s
Grant ID: ASAP-020370
Abstract
A structure-activity relationship-based modification of pyrimidine-2,4,6-triones led to 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2,4,6-(1H,3H,5H)-trione (CP8), a potent and highly selective CaV1.3 L-type calcium channel antagonist. This protocol is an adaption of Kang, S., Cooper, G., Dunne, S. et al., 2012's method of the synthesis of this chemical.
Guidelines
All solvents and reagents were used as supplied (analytical or HPLC grade) without prior purification. Water was purified by an Elix® UV-10 system. In vacuo refers to the use of a rotary evaporator attached to a diaphragm pump.

Thin layer chromatography was performed on aluminium plates coated with 60 F254 silica.

Plates were visualised using UV light (254 nm) or 1% aq. KMnO4. Flash column chromatography was performed on Kieselgel 60M silica in a glass column.

Nuclear magnetic resonance (NMR) spectra were recorded on Bruker Avance spectrometers (AVIII 400) in the deuterated solvent stated. The field was locked by external referencing to the relevant deuteron resonance. Chemical shifts (d) are reported in parts per million (ppm) referenced to the solvent peak. 1H spectra reported to two decimal places (see Figure 2), and 13C spectra reported to one decimal place (see Figure 3), and coupling constants (J) are quoted in Hz (reported to one decimal place).

Low-resolution mass spectra were recorded on an Agilent 6120 spectrometer from solutions of MeOH.  


Figure 2 - 1H NMR Spectra


Figure 3 - 13C NMR Spectra


Materials
Equipment:

Reagents:
  • 2-(3-chlorophenyl)ethylamine ( 2.58 mmol, 1.0 eq)
  • Cyclopentaneisocyanate (2.58 mmol, 1.0 eq)
  • Dichloromethane
  • Kiesegel 60M Silica
  • Malonyl chloride (2.84 mmol, 1.1 eq)

Synthesis of 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2,4,6-(1H,3H,5H)-trione (CP8)
Synthesis of 1-(3-chlorophenethyl)-3-cyclopentylpyrimidine-2,4,6-(1H,3H,5H)-trione (CP8)
Add 357 µL 2-(3-chlorophenyl)ethylamine (2.58 mmol, 1.0 eq.) to a solution of 290 mg of Cyclopentaneisocyanate (2.58 mmol, 1.0 eq.) in 10 mL of dichloromethane.
Stir at RT for 5 h.
Monitor completion with Low-Resolution Mass Spectrometry.
Add 276 µL Malonyl chloride (2.84 mmol, 1.1 eq.) dropwise under vigorous stirring over 5 min.
Stir mixture for 1 h and concentrate in vacuo.
Purify residue by column chromatography on silica gel (EtOAc/pentane, 1:4), product should be a white solid (687 mg, 80%)
Nuclear Magnetic Resonance (NMR) Spectroscopy
Nuclear Magnetic Resonance (NMR) Spectroscopy
Check data from NMR spectroscopy is comparable with the literature (Kang, S., Cooper, G., Dunne, S. et al., 2012):

1H NMR (400 MHz, CDCl3) δ 7.25 – 7.19 (m, 3H), 7.13 (dt, J = 6.7, 2.1 Hz, 1H), 5.20 – 5.07 (m, 1H), 4.13 – 4.03 (m, 2H), 3.62 (s, 2H), 2.92 – 2.84 (m, 2H), 1.94 (tqd, J = 8.0, 4.9, 2.0 Hz, 4H), 1.89 – 1.79 (m, 2H), 1.61 – 1.57 (m, 2H)

13C NMR (101 MHz, CDCl3) δ 164.9, 164.6, 151.1, 140.0, 134.5, 123.0, 129.2, 127.3, 127.1, 54.6, 42.8, 40.3, 33.8, 28.8, 25.7; LRMS m/z (ESI¯) 333.1 [M-H]¯


Note
The multiplicity of each signal is indicated by: δ (singlet); br. s (broad singlet); d (doublet); t (triplet); q (quartet); dd (doublet of doublets); td (triplet of doublets); qt (quartet of triplets); or m (multiplet).

Protocol references
Kang, S.; Cooper, G.; Dunne, S. F.; Dusel, B.; Luan, C.-H.; Surmeier, D. J.; Silverman, R. B. CaV1.3-selective L-type calcium channel antagonists as potential new therapeutics for Parkinson's disease. Nature Communications 2012, 3 (1), 1146. DOI: 10.1038/ncomms2149.