General Methods. All reactions were performed under a nitrogen atmosphere using dry solvents unless otherwise stated. NMR spectra were recorded on a 400 MHz spectrometer. High-resolution mass spectra (HRMS) were obtained using ESI-TOF.
Synthesis of (E)-7-[(1R,2R,3R)-3-hydroxy-2-[(E)-(3S)-3-hydroxy-4-(3-methyloxetan-3-yl)but-1-enyl]-5-oxocyclopentyl]hept-5-enoic acid (Compound 4β).
Step 1: Formation of Boronic Ester 2. To a solution of cyclopentenone 1 (5.0 g, 22 mmol) in dioxane (100 mL) was added bis(pinacolato)diboron (6.7 g, 26 mmol), Pd(dppf)Cl₂ (800 mg, 1.1 mmol), and KOAc (6.5 g, 66 mmol). The mixture was heated to 80 °C for 12 h. After cooling, the mixture was filtered through Celite and concentrated. Purification by silica gel chromatography (Hexane/EtOAc 4:1) yielded 2 (5.8 g, 85%) as a colorless oil.
Step 2: Stereoselective Reduction. To a solution of ketone 5 (2.0 g, 4.2 mmol) in dry THF (50 mL) at -78 °C was added L-Selectride (1.0 M in THF, 5.0 mL, 5.0 mmol) dropwise. The reaction was stirred for 2 h at -78 °C. The reaction was quenched with NaOH solution and H₂O₂, warmed to room temperature, and extracted with EtOAc. The organic layer was dried over Na₂SO₄ and concentrated. The diastereomers were separated via flash chromatography to isolate the desired 4β isomer.
Step 3: Hydrolysis. To a solution of the ester (1.0 g, 2.0 mmol) in MeOH/THF/H₂O (1:1:1, 30 mL) was added LiOH·H₂O (168 mg, 4.0 mmol). The reaction was stirred at 25 °C for 4 h. The solvent was removed under reduced pressure, and the residue was purified by reverse-phase HPLC to yield the title compound as a white solid. the synthetic ep 4 beta by carbon work
Data for Compound 4β: ¹H NMR (400 MHz, CDCl₃) δ 5.78 (dd, J = 15.2, 6.8 Hz, 1H), 5.52 (m, 2H), 4.21 (m, 1H), 3.90 (m, 1H), 2.45 (t, J = 7.2 Hz, 2H), 2.30 (m, 1H), 1.25 (s, 3H). HRMS (ESI) m/z: [M+H]⁺ Calcd for C₂₃H₃₅O₅ 391.2484; Found 391.2481. [α]D²⁵ = +45.2° (c 1.0, MeOH).
A likely reading:
"Synthesis of epoxide 4-beta (a β-epoxide on a 4-carbon chain or at the 4-position) using carbon-based methods."
Example reaction:
Without a specific compound name or reaction scheme, this remains speculative. Unlocking Molecular Complexity: A Deep Dive into The
The synthesis is divided into three phases: Peptide Backbone Assembly, Epoxyketone Warhead Construction, and Final Coupling.
Stereoselective Synthesis and Biological Evaluation of a Novel Carbocyclic EP4 Receptor Agonist: “Compound 4β”
Authors: Alex Mercer¹*, Sarah Jenkins¹, David Chen² ¹ Department of Organic Chemistry, University of Applied Sciences ² Department of Pharmacology, Institute of Translational Medicine
Abstract: The Prostaglandin E2 receptor 4 (EP4) plays a critical role in bone healing, inflammation resolution, and gastrointestinal mucosal protection. While natural prostaglandins suffer from rapid metabolic degradation and systemic side effects, synthetic agonists offer improved stability and selectivity. This paper details the total synthesis of a novel, high-affinity EP4 agonist, designated Compound 4β. The synthetic route features a palladium-catalyzed cross-coupling strategy to construct the key cyclopentane core, followed by a stereoselective reduction to establish the requisite β-orientation at the C-15 hydroxyl group. The synthetic pathway achieves an overall yield of 14% over 12 linear steps. Preliminary biological evaluation demonstrates that Compound 4β exhibits nanomolar affinity for the EP4 receptor (IC₅₀ = 2.4 nM) with a metabolic stability profile superior to that of native PGE2, making it a promising candidate for further preclinical development. Epoxidation of a β,γ- or β,δ-unsaturated system with
Keywords: EP4 Agonist, Prostaglandin Analogue, Stereoselective Synthesis, Bone Healing, Palladium Catalysis.
Most routes begin with a [3+2] cycloaddition or a Nazarov cyclization. However, the most elegant carbon work approach reported utilizes a palladium-catalyzed asymmetric allylic alkylation (AAA) between a prochiral enolate and an allylic acetate. This forms the first crucial C-C bond with >98% enantiomeric excess (ee).
The result is a highly functionalized cyclopentenone, which serves as the "beta" platform. The term "beta" here refers to the orientation of the hydroxy group at C11 (prostaglandin numbering), which must be set to the β-configuration (above the plane) to mimic natural PGE2’s bioactive conformation.
No material is without drawbacks. Current challenges for the synthetic EP 4 beta by carbon work include:
Research groups at MIT and the Max Planck Institute for Polymer Research are actively pursuing two solutions: a continuous flow synthesis for the carbon work step, and a reversible Diels–Alder tether that would allow the EP 4 beta to be “unlocked” and re-formed at end of life.