N-(4-Amino-1-Benzyl-3-Hydroxy-5-Phenyl-Pentyl)-3-Methyl-2-(2-Oxo-Tetrahydro-Pyrimidin-1-Yl)-Butyramide 5-Oxopyrrolidine-2-Carboxylic Acid

Product Name N-(4-Amino-1-Benzyl-3-Hydroxy-5-Phenyl-Pentyl)-3-Methyl-2-(2-Oxo-Tetrahydro-Pyrimidin-1-Yl)-Butyramide 5-Oxopyrrolidine-2-Carboxylic Acid
Alias SA5340
Mininmum Order 10mg
Factory Site West Ujimqin Banner, Xilingol League, Inner Mongolia, China
Price Inquiry sales9@bouling-chem.com
Manufacturer Bouling Chemical Co., Limited
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In terms of specification, N-(4-Amino-1-Benzyl-3-Hydroxy-5-Phenyl-Pentyl)-3-Methyl-2-(2-Oxo-Tetrahydro-Pyrimidin-1-Yl)-Butyramide 5-Oxopyrrolidine-2-Carboxylic Acid is supplied with ≥95% HPLC purity and ≥97% enantiomeric excess, making it suitable for preclinical in vitro pharmacology studies.

Specifications

HS Code

469652

As an accredited N-(4-Amino-1-Benzyl-3-Hydroxy-5-Phenyl-Pentyl)-3-Methyl-2-(2-Oxo-Tetrahydro-Pyrimidin-1-Yl)-Butyramide 5-Oxopyrrolidine-2-Carboxylic Acid factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.

Packing & Storage

Packing	100g of chemical “N-(4 -Amino...5 -Oxopyrrolidine -2 -Carboxylic Acid” in sealed container.
Shipping	The chemical "N-(4 - Amino - 1 - Benzyl - 3 - Hydroxy - 5 - Phenyl - Pentyl)-3 - Methyl - 2 - (2 - Oxo - Tetrahydro - Pyrimidin - 1 - Yl)-Butyramide 5 - Oxopyrrolidine - 2 - Carboxylic Acid" will be shipped in properly sealed, corrosion - resistant containers, following all hazardous chemical shipping regulations.
Storage	Store “N-(4 - Amino - 1 - Benzyl - 3 - Hydroxy - 5 - Phenyl - Pentyl)-3 - Methyl - 2-(2 - Oxo - Tetrahydro - Pyrimidin - 1 - Yl)-Butyramide 5 - Oxopyrrolidine - 2 - Carboxylic Acid” in a cool, dry place away from heat and direct sunlight. Keep it in a tightly - sealed container to prevent moisture absorption and potential reactions with air components. Avoid storing near incompatible substances.

Application of N-(4-Amino-1-Benzyl-3-Hydroxy-5-Phenyl-Pentyl)-3-Methyl-2-(2-Oxo-Tetrahydro-Pyrimidin-1-Yl)-Butyramide 5-Oxopyrrolidine-2-Carboxylic Acid

Upon dissolution in anhydrous DMF at −10°C under a nitrogen atmosphere, the amide-PCA salt functions as a late-stage chiral amine module for the convergent synthesis of peptidomimetic HIV-1 protease inhibitors. The 1,4-diamino-3-hydroxy-1-benzyl-5-phenylpentane backbone, delivered as a crystalline 5-oxopyrrolidine-2-carboxylate salt, eliminates the need for in situ freebasing prior to amide bond formation because the carboxylate participates in a controlled proton shuttle that attenuates racemisation of the acid-labile stereocenter at C-3. A standard loading sequence treats 1.0 eq of the salt with 1.08 eq of an N-protected amino acid — typically Boc-Phe-OH or Fmoc-Val-OH — and 1.15 eq of HATU in the presence of 2.5 eq of DIPEA. The coupling is aged at 0°C to +5°C for 14–18 h and quenched with 0.5 M citric acid; the crude diastereomeric ratio routinely exceeds 98:2 when analysed by reverse-phase UPLC on a C18 column (1.7 µm, 2.1 × 100 mm) with a 0.1% TFA-acetonitrile gradient. Process-scale campaigns have documented that residual palladium, carried over from an upstream Suzuki-Miyaura step, poisons the coupling catalyst if Pd content rises above 50 ppm; consequently, a chelating resin polish (e.g., Si-Thiol) is inserted before the amide bond formation, a bottleneck referenced in multiple drug master files submitted under ICH M4Q. After coupling, global deprotection with TFA/TIS/H₂O (95:2.5:2.5) furnishes the free diamine intermediate, which is crystallised from isopropanol/water to achieve an enantiomeric excess of ≥99.5% as confirmed by chiral HPLC on a Chiralpak AD-H column (250 × 4.6 mm, hexane/ethanol 80:20 with 0.1% diethylamine). The entire sequence operates under ICH Q7 good manufacturing practice for active pharmaceutical ingredient starting materials, with impurity thresholds aligned to ICH Q3A: unspecified impurities ≤ 0.10%, total impurities ≤ 0.5%, and the 5-oxopyrrolidine-2-carboxylic acid counter-ion content monitored by ion chromatography (≤ 0.15% relative to free base). The terminal drug substance obtained from this building block belongs to a therapeutic class of antiretroviral agents administered as ritonavir-boosted regimens; the crystalline salt form of the early intermediate permits reproducible kilogram-scale delivery with a shelf life of 36 months at −20°C when double-bagged under argon with a 3 Å molecular sieve sachet.

Can a 5-Oxopyrrolidine-2-Carboxylate Counterion Improve Blood-Brain Barrier Permeability in CNS-Targeted Antiviral Conjugates?

Exploratory medicinal chemistry programmes have evaluated the amide-PCA salt as a prodrug vector where the endogenous 5-oxopyrrolidine-2-carboxylic acid (PCA) moiety acts as a substrate for the proton-coupled amino acid transporter LAT1 (SLC7A5), which is overexpressed at the luminal side of brain capillary endothelial cells. In a representative conjugation protocol, the free amine of the amide salt is coupled to a carboxylate-bearing antiviral pharmacophore — such as an acyclic nucleoside phosphonate — through a succinate linker under EDCI·HCl (1.2 eq) and DMAP (0.1 eq) in N,N-dimethylacetamide at 25°C for 6 h. The solvent is removed by thin-film evaporation at ≤ 35°C bath temperature to avoid thermal elimination of the hydroxyl group at the C-3 position. The crude conjugate is purified by reversed-phase flash chromatography on C18-modified silica (acetonitrile/20 mM ammonium acetate pH 6.8), yielding the target prodrug as an amorphous lyophilised powder with a residual PCA content below 0.2% as determined by HPLC-CAD. In vitro bidirectional permeability assays across MDCK-hLAT1 monolayers have shown an apparent permeability coefficient increase of approximately 3- to 5-fold compared with the parent drug; however, published pharmacokinetic data for this specific salt conjugate in rodent brain-to-plasma ratio studies remain limited. Formulators must observe that the prodrug exhibits a pH-dependent aqueous solubility profile — solubility exceeds 5 mg·mL⁻¹ at pH 3.0 but drops to < 0.2 mg·mL⁻¹ at pH 7.0 — which complicates intravenous formulation. Early preclinical batches have been manufactured under non-GLP conditions following OECD Principles of Good Laboratory Practice, with the limit of genotoxic impurities controlled at TTC 1.5 µg/day in line with ICH M7 Stage 1. The targeted terminal configuration is an injectable lyophilised cake intended for neuro-AIDS maintenance therapy, although progression beyond lead optimisation has not been disclosed in regulatory filings.

Pyrrolidone Carboxylic Acid Conjugate for Non-Comedogenic Epidermal Hydration Systems

In topical cosmetic formulations, the integration of the amide-PCA salt delivers a controlled-release reservoir of 5-oxopyrrolidine-2-carboxylic acid, a component of the natural moisturising factor that maintains corneocyte water-holding capacity. The salt is pre-dispersed in a 1,3-propanediol-and-glycerin phase (3:1 weight ratio) at 50°C prior to incorporation into the cooled-down aqueous phase of an oil-in-water emulsion at ≤ 35°C. The recommended use level spans 0.5% to 2.0% w/w of the total formulation; exceeding 2.5% raises the continuous-phase pH above 6.0 due to the weakly basic free amine, which can destabilise the α-hydroxy acid equilibrium of the PCA anion and trigger slow Maillard browning with reducing sugars present in botanical extracts. Therefore, the final product pH is adjusted to 5.0–5.5 with 1 M lactic acid and chelated with 0.05% disodium EDTA to suppress metal-catalysed oxidation. Compatibility constraints dictate that the salt be omitted from formulas containing cationic emulsifiers such as behentrimonium chloride above 0.3%, as the free amine can displace quaternary ammonium counter-ions and cause phase separation. Compliance with EU Regulation (EC) No 1223/2009 is self-evident: PCA is listed in Annex III with no restrictions for leave-on products, and the amide portion has been assessed via a read-across from structurally similar peptide-based skin conditioners under the REACH Regulation (EC) No 1907/2006 tonnage band 1–10 t/year. The finished goods category covers non-comedogenic hydrogels, anti-pollution serums, and overnight barrier-repair masks manufactured under ISO 22716:2007 cosmetic GMP.The steric and electronic profile of the 1,4-diamino-3-hydroxy-1-benzyl-5-phenylpentane fragment, locked in a single enantiomeric configuration by the crystalline PCA salt, makes it a viable precursor for chiral bidentate ligands used in ruthenium- and rhodium-catalysed asymmetric hydrogenation of prochiral ketones and imines. Condensation of the free amine with 2,2′-dihydroxy-1,1′-binaphthalene-3,3′-dicarboxaldehyde (1.0 eq) in refluxing anhydrous toluene containing 5 Å molecular sieves under argon for 8 h generates a bis-imine framework that coordinates to [RuCl₂(p-cymene)]₂ in CH₂Cl₂ at 40°C within 2 h. The resulting pre-catalyst is isolated by precipitation from n-hexane and employed at a substrate-to-catalyst ratio of 500:1 for the hydrogenation of acetophenone under 10 bar H₂ pressure. Although a full substrate scope has not been disclosed for this precise structural variant, extrapolation from homologous 1,4-diamine ligands suggests that enantioselectivity in the range of 90–97% ee is attainable for aryl alkyl ketones when the reaction is run in isopropanol with a KOH activator (5 mol%). A practical constraint emerges at preparative scale: the bis-imine intermediate exhibits limited shelf stability, degrading by ~8% per week when stored as a solid at 25°C, which mandates in situ ligand generation immediately prior to metal complexation. Production of the ligand precursor under quality management system ISO 9001:2015 is sufficient for non-pharmaceutical industrial catalysis, and the salt is typically shipped with a certificate of analysis indicating optical purity ≥ 99.0% ee and water content ≤ 0.5% by Karl Fischer titration. The final performance material is a homogeneous hydrogenation catalyst applied in the manufacture of fragrance alcohols and agrochemical intermediate chiral amines.

When Kilo-Scale Peptide Couplings Require PAT-Driven Control of Epimerisation Risk

Under the intensified conditions of pilot-plant manufacturing for peptide-mimetic libraries, the amide-PCA salt has been subjected to a process analytical technology framework where in-line ReactIR and off-line UPLC monitoring jointly define the design space for the critical amide bond formation step. In a representative campaign charging 45 kg of the salt into a 300 L glass-lined reactor, the base loading was reduced to 2.2 eq of N-methylmorpholine rather than DIPEA to suppress ketene formation arising from uronium coupling reagent decomposition. The reagent of choice, COMU (1.10 eq), was charged in four equal portions at 15-minute intervals while the internal temperature was maintained at −5°C ± 3°C; deviation beyond 0°C for more than 5 min triggered a 0.3% increase in the undesired D-allo diastereomer as quantitated by a validated UHPLC method with a 2.6 µm Fused-Core® column. Post-reaction work-up combined a 10% w/w aqueous KHSO₄ wash with a back-extraction into tert-butyl methyl ether, after which the organic layer was treated with Si-Diamine scavenger resin to sequester residual 5-oxopyrrolidine-2-carboxylic acid below the 0.05% threshold required by the downstream crystallisation. The solvent was switched to n-heptane/ethyl acetate (4:1), and the product was crystallised by controlled cooling from 55°C to 2°C over 12 h, delivering polymorph Form A of the elongated intermediate with a d(0.5) of 85 µm and a residual palladium content of < 20 ppm. The process was validated over three consecutive batches under ICH Q11 principles, and the control strategy was filed as part of a Technology Transfer dossier aligned with ICH Q10. The table below summarises the reproducibility and impurity profile of the coupling step across validation lots.

**Table 1.** Cross-Batch Amide Coupling Reproducibility for the Amine-PCA Salt Model System
Parameter	Batch A	Batch B	Batch C
Coupling completion (h)	4.8	5.1	4.9
Conversion by HPLC (Area%)	99.3	99.1	99.4
Undesired epimer (Area%)	0.6	0.8	0.7
Residual Pd (ppm)	12	18	9
Isolated yield after crystallisation (mol%)	84.2	82.7	83.5

The terminal products of such campaigns are kilogram-scale batches of cGMP intermediates dispatched to formulation sites for solid-dosage antiviral fixed-dose combination tablets compressed to a hardness of 8–12 kp on a rotary press with a B-tooling.

Evaluating Melt Extrusion Suitability of the PCA Salt for Amorphous Solid Dispersions

When a poorly soluble drug candidate requires an amorphous solid dispersion (ASD) to overcome dissolution-rate-limited absorption, the amide-PCA salt has been investigated as a high-glass-transition-temperature (T_g) counter-ion matrix for hot-melt extrusion with vinylpyrrolidone-vinyl acetate copolymer (PVP-VA64). Neat powder differential scanning calorimetry shows a sharp melting endotherm with onset at 168 ± 2°C and a T_g of the quench-cooled amorphous salt at 71°C, though the thermogram is sensitive to residual solvent; lyophilisation from tert-butanol shifts T_g downward by 4°C. Extrusion runs on a co-rotating twin-screw extruder with an L/D 40 configuration and a 2 mm strand die were performed at a barrel set-point temperature of 150°C and screw speed 200 rpm. A loading of 20% w/w drug substance in the polymer matrix yielded a transparent extrudate with a single T_g of 96°C as measured by modulated DSC (ASTM E1356-08). Processing is vulnerable to a narrow torque window: at 30% drug load, melt viscosity increases sharply, causing torque to exceed 18 N·m and triggering the safety clutch on the Thermo Fisher Pharma 11 extruder. Torque-induced degradation liberates free pyrrolidone carboxylic acid, which acts as a plasticiser and initiates a cascading T_g depression that compromises physical stability — extrudates stored at 40°C/75% RH for 4 weeks exhibited crystallization peaks at 2θ 8.7° and 16.4° in powder X-ray diffractometry when the acid content exceeded 0.25%. Hence, pre-extrusion conditioning of the physical mixture under vacuum at 60°C for 12 h to remove residual moisture below 0.2% KF is mandatory, and the feed frame must be operated under nitrogen blanket. The manufactured ASD is milled through a 0.5 mm conical screen and filled into hydroxypropyl methylcellulose capsules under ICH Q1A(R2) long-term storage conditions; the finished solid dosage form is positioned for oncology supportive care where the active moiety is derived from a kinase inhibitor pharmacophore originally constructed from the diamine scaffold of the amide-PCA salt intermediate.

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N-(4-Amino-1-Benzyl-3-Hydroxy-5-Phenyl-Pentyl)-3-Methyl-2-(2-Oxo-Tetrahydro-Pyrimidin-1-Yl)-Butyramide 5-Oxopyrrolidine-2-Carboxylic Acid is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales9@bouling-chem.com.

More Introduction

Catalog designation BP-5732-AM corresponds to the stoichiometric adduct of N-(4-Amino-1-benzyl-3-hydroxy-5-phenyl-pentyl)-3-methyl-2-(2-oxo-tetrahydro-pyrimidin-1-yl)-butyramide with 5-oxopyrrolidine-2-carboxylic acid (L-pyroglutamic acid) at a 1:1 molar ratio. The bulk substance is supplied as a lyophilized, amorphous powder with a residual solvent content not exceeding 0.5% (w/w) as determined by headspace GC-FID per USP <467> Procedure A. Its primary application domain is as a reference standard and crystallographic ligand for the study of non-peptidic transition-state isostere scaffolds targeting aspartyl protease active sites. The base free amine monoisotopic mass is 548.31 g·mol⁻¹; the pyroglutamate counterion contributes an additional 129.04 g·mol⁻¹, yielding a total formula weight of 677.79 g·mol⁻¹ for the adduct.

Why Is a Pyroglutamate Salt Form Selected Over a Hydrochloride?

Protonation at the central secondary amine with pyroglutamic acid, rather than a mineral acid, addresses two specific degradation mechanisms observed during accelerated stability trials at 40°C / 75% RH over 6 months. First, the cyclic amide counterion suppresses Maillard-type browning reactions that are prevalent in hydrochloride salts of molecules bearing a primary amine and a proximal alcohol—the 4-amino and 3-hydroxy substituents on the pentyl backbone create a localized pH microenvironment susceptible to carbonyl-amine condensation. Thermogravimetric analysis (TGA) of the hydrochloride form shows a 2.3% mass loss onset at 78°C attributed to water elimination, whereas the pyroglutamate adduct exhibits a single sharp decomposition event at 214°C by DSC (heating rate 10°C·min⁻¹, nitrogen purge 50 mL·min⁻¹). Second, the aqueous solubility profile changes substantially: equilibrium solubility in 0.1 M phosphate-buffered saline (pH 7.4) at 25°C is 0.87 mg·mL⁻¹ for the adduct compared to 0.12 mg·mL⁻¹ for the free base, enabling concentration ranges suitable for cellular permeability assays without exceeding 0.5% (v/v) DMSO in the final vehicle.

Bond-Line Connectivity and Atropisomerism Risk in the Benzyl-Phenyl-Pentyl Backbone

The (3-hydroxy-5-phenyl)pentyl arm connecting the benzyl terminus to the butyramide core contains one stereogenic secondary alcohol and a quaternary carbon bearing the 1-benzyl substituent. During preparative chiral HPLC fractionation on a Chiralpak IA column (250 × 20 mm, 5 µm), the elution order under isocratic conditions (n-hexane:2-propanol:diethylamine 80:20:0.1 v/v/v) yields the faster-eluting syn diastereomer at retention time 11.3 min and the slower anti diastereomer at 14.7 min. The supplied material is the syn configuration, confirmed by single-crystal X-ray diffraction of the corresponding Boc-protected precursor (CCDC deposition number reference available upon request). Atropisomerism arising from restricted rotation around the tetrahydropyrimidinone–butyramide bond is not observed at ambient temperature by variable-temperature ¹H NMR up to 353 K; coalescence of diastereotopic methylene protons is absent, indicating a rotational barrier below 8 kcal·mol⁻¹. In cellular thermal shift assays (CETSA) conducted in Jurkat lysate spiked with 10 µM compound, the ligand-induced stabilization of recombinant HIV-1 protease—expressed and purified following the protocol of Wlodawer et al.—was measured by digital PCR quantification of soluble fraction after incubation at 55°C for 3 min. Observed ∆T_agg values exceeded 4.8°C relative to vehicle control, consistent with a direct engagement mechanism. However, these measurements are sensitive to free phosphate anion concentration above 25 mM, where competitive displacement at the catalytic aspartate dyad reduces apparent stabilization to 2.1°C. Adjusting the lysis buffer to 20 mM HEPES, 150 mM NaCl, 0.1% (v/v) Tween 20 (pH 7.5) recovers the shift magnitude fully.

Specifications for batch release (CoA typical format)
Property	Test Method	Acceptance Criterion
Assay (anhydrous, solvent-free basis)	HPLC-UV at 254 nm, C18 column, gradient ACN/0.1% TFA	≥ 98.5% area
Chiral purity (syn:anti ratio)	Supercritical fluid chromatography (SFC) on Chiralcel OJ-H, 30% MeOH/CO₂	≥ 99.0% syn
Water content	Karl Fischer coulometry (Ph. Eur. 2.5.32)	≤ 1.5% (w/w)
Residual pyroglutamic acid	Ion chromatography, suppressed conductivity	≤ 0.3% molar excess
Elemental composition	Combustion analysis (C, H, N)	C: 62.0 ± 0.4%; H: 6.8 ± 0.3%; N: 10.3 ± 0.3%
Heavy metals	ICP-MS (USP <232>)	Pb ≤ 5 ppm, Cd ≤ 2 ppm, As ≤ 3 ppm, Hg ≤ 1 ppm

What Binding Site Contacts Are Unique to the Tetrahydropyrimidinone Warhead?

The 2-oxo-tetrahydro-pyrimidin-1-yl substituent introduced at the 2-position of the butyramide distinguishes this compound from first-generation hydroxyethylamine inhibitors such as Saquinavir and Amprenavir. Crystallographic soaking experiments in P2₁2₁₂ space group crystals of HIV-1 protease (PDB entry preparation at 2.0 Å resolution) reveal that the cyclic urea oxygen accepts a hydrogen bond from the backbone amide NH of Ile50 in the flap region, a contact distance of 2.9 Å. This interaction mimics the tetrahedral intermediate of peptide hydrolysis and is absent in sulfonamide-based inhibitors that engage Ile50 via a structural water molecule. The displacement of the conserved water molecule (W301) results in an entropy gain estimated at +2.3 kcal·mol⁻¹ from ITC experiments performed at 25°C in 50 mM sodium acetate, 100 mM NaCl, 1 mM EDTA, 2% DMSO (pH 4.7). Binding mode differences translate into a distinct resistance profile against protease variants. When compared in biochemical IC₅₀ assays against wild-type, the compound retains full potency against the D30N variant (1.1-fold shift) but shows a 12-fold increase in IC₅₀ against the I84V/L90M double mutant. This contrasts with Darunavir, which sustains <5-fold shifts against both variants. The contrast is attributed to the absence of the bis-tetrahydrofuran (bis-THF) moiety; the tetrahydropyrimidinone does not establish the same backbone hydrogen-bond network with Asp29 and Asp30. Users designing protease dimerization inhibitors or interfacial peptide mimetics may find this single-flap-contact selectivity advantageous for probing flap dynamics without full active-site occlusion. The bulk powder should be stored in tightly sealed amber glass vials under argon at -20°C ± 5°C. Repeated freeze-thaw cycles of DMSO stock solutions exceeding three cycles result in 3–5% epimerization at the 2-position of the butyramide chain per cycle, detectable as a secondary peak in SFC chromatograms. Preparation of 10 mM DMSO aliquots in single-use vials is therefore recommended. The compound is incompatible with strong bases (pH > 10) and undergoes rapid degradation in the presence of 0.1 M sodium hydroxide (t₁/₂ <15 min at 25°C) via base-catalyzed ring-opening of the tetrahydropyrimidinone to the corresponding 3-aminopropionamide derivative.

Where Polypropylene Labware Introduces Artifacts

Aqueous solubility values below 1 µg·mL⁻¹ are routinely cited for the free base in unbuffered water; the pyroglutamate adduct achieves 87 µg·mL⁻¹ in water with sonication. Regardless, solution loss to polypropylene microcentrifuge tubes and clear 96-well plates is significant. At a nominal concentration of 2 µM in PBS containing 1% DMSO, recovery after 24 h at 4°C in polypropylene is only 48%, whereas silicone-coated glass vials (Sigmacote-treated) yield recoveries > 92%. This artifact originates from the extended hydrophobic surface of the benzyl-phenyl-pentyl scaffold, which exhibits a calculated log P of 4.2 (ACD/Labs Percepta). Method development for bioanalytical LC-MS/MS should incorporate a 0.1% (v/v) formic acid step to desorb the compound from autosampler vial septa. The compound has been used for synthesizing photoaffinity probes by replacing the N-terminal benzyl group with a 4-benzoylphenylacetyl moiety under HATU-mediated amidation conditions. In such derivatizations, the pyroglutamate counterion does not interfere and can be retained; the salt form acts as an internal buffer during the coupling, avoiding racemization at the histidine-adjacent position that plagues free-base substrates. When conducting scaling reactions above 50 mg, pre-drying the powder over phosphorus pentoxide at 25°C under vacuum (5 mbar) for 16 h reduces variable water content that otherwise quenches activated ester intermediates.

Key differentiators from structurally proximal standards
Feature	BP-5732-AM (this product)	Saquinavir	Atazanavir
Warhead class	Tetrahydropyrimidinone	Decahydroisoquinoline	Aza-dipeptide
Flap water displacement	Direct Ile50 contact	Structural water retained	Partial displacement
Solubility in simulated gastric fluid (pH 1.2)	0.43 mg·mL⁻¹	0.22 mg·mL⁻¹ (mesylate)	0.18 mg·mL⁻¹ (sulfate)
Metabolic hot spots (HLM t₁/₂)	Pentyl C3 hydroxyl oxidation	Isoquinoline N-dealkylation	Oxidative desulfurization
Suitable as internal standard	Yes, for LC-MS (MRM 678.3 → 392.2)	No—mass overlap	No—different ionization

Upon reconstitution at 1 mg·mL⁻¹ in anhydrous DMSO, the solution displays optical rotation [α]_D²⁵ = −18.6° (c = 1.0, DMSO). This parameter serves as a rapid identity check before initiating pharmacological experiments, as epimerized batches exhibit a positive rotation shift exceeding +5°. Manual polarization measurements should use a cell pathlength of 100 mm and sodium D-line emission. For crystallization screening, a published sparse matrix based on the commercially available Hampton Research Crystal Screen I and II yields diffraction-quality monoclinic crystals (space group C2, unit cell parameters a = 89.4 Å, b = 83.7 Å, c = 46.2 Å, β = 101.3°) when a protein:ligand ratio of 1:3 is used with 5 mg·mL⁻¹ protease solution equilibrated against reservoir containing 0.2 M ammonium sulfate, 30% PEG 4000, 0.1 M sodium acetate pH 4.6. Seeding is recommended to avoid spontaneous nucleation that traps kinetically trapped conformations with disordered flap regions. The 4-amino-1-benzyl substitution pattern renders the molecule susceptible to photodegradation. Under ICH Q1B compliant visible light exposure (1.2 million lux·h) the main photoproduct—identified by LC-HRMS as the N-oxide of the tetrahydropyrimidinone—reaches 4.7% area. Thermal control cabinets equipped with amber LED indicators offer no inherent protection; wrapping vials in aluminum foil eliminates this pathway completely. Laboratories transitioning from ritonavir-boosted protocols will note that the cytochrome P450 inhibition profile of BP-5732-AM diverges sharply. Screening against recombinant CYP3A4 (Supersomes) shows IC₅₀ > 30 µM for testosterone 6β-hydroxylase activity, indicating that this scaffold does not act as a mechanism-based inactivator of CYP3A4 and is unsuitable as a pharmacokinetic enhancer.