I.The practical problem: Why does R&D so often “swap in a small ring” to gain controllability?
In catalysis, materials development, and synthetic R&D, repeated rework is often not because “the target molecule can’t be made,” but because results are hard to reproduce, hard to rationalize, and hard to scale. The bottlenecks commonly show up at three levels:
1. Selectivity is hard to stabilize
Under the same nominal conditions, enantioselectivity/regioselectivity may be extremely sensitive to tiny changes in substrate, solvent and moisture, temperature, or concentration—so results “drift” when you change a substrate batch or even open a new bottle of solvent.
2. Property windows are hard to align
Solubility, polarity, interfacial behavior, stability, and processability (viscosity/film formation/curing) often cannot be optimized simultaneously: improving one metric can noticeably worsen another.
3. Intermediates are hard to handle
Key intermediates may be too reactive, too conformationally flexible, or have functional groups that “interfere with each other,” leading to side reactions, difficult separations, unstable scale-up, and batch-to-batch variability.
Oxazolines and oxazolidines (more often referring to oxazolidines, i.e., N,O-acetals/hemiaminals) appear frequently in R&D for a fundamental reason: with very little added steric bulk, they replace “uncontrollable system sensitivity” with “designable structural variables.” That makes it easier to explain results in structural terms and to stabilize the operational window.
R&D pain point | “Controllable variables” small rings typically introduce | Typical role of oxazolines/oxazolidines |
Selectivity drift; high sensitivity to conditions | Clearer geometric constraints and localized chiral environments; more predictable coordination/interaction patterns | Oxazolines: often serve as coordination units dominated by the ring N, combined with another N or P donor to form multidentate chiral ligands (e.g., BOX / PyBOX / PyOX / PHOX; N,N / N,N,N / P,N motifs), stabilizing selectivity via modular structures. |
Misaligned property windows (solubility/polarity/interface/stability are hard to balance) | Introduce local polarity + rigidity + acceptor sites without markedly increasing scaffold size; fine-tune solvation and packing | Oxazolines: commonly used as low-volume, readily substituted polar modules for property tuning; ligand applications are covered in systematic reviews. |
Reactive intermediates; difficult purification; unstable scale-up | Use temporary cyclization to convert reactive sites into more stable, easier-to-weigh forms; later enable mild ring opening/hydrolysis back to the target functional group | Oxazolidines (N,O-acetals): widely used for protection of amino alcohol fragments and for temporary conformational locking—classic N,O-acetal protecting logic. |
II.Basic concepts: four easily confused terms
The names “oxazoline / oxazolidine / oxazolidinone / oxazole” are the most likely to be mixed up or misread. All relate to N and O, but they correspond to different electronic structures and serve different roles in research.
Name | Core structural distinction | Typical role in research |
Oxazoline (most often 2-oxazoline) | Partially unsaturated N,O five-membered ring (“saturation between aromatic oxazole and fully saturated oxazolidine”); positional isomers of the double bond can exist in nomenclature, but in research and catalogs the default usually refers to the 2-oxazoline scaffold | Fragment in asymmetric catalysis ligands (key unit in BOX/PyBOX families); 2-oxazoline monomers for cationic ring-opening polymerization to form poly(2-oxazoline) material platforms |
Oxazolidine (1,3-oxazolidine) | Fully saturated N,O five-membered ring; commonly a cyclic N,O-acetal (N,O-acetal, oxazolidine) formed by condensation of a β-amino alcohol with an aldehyde/ketone; often an acid/water-sensitive protecting form | Protection and temporary “locking” of amino alcohols: simultaneously masks amine/alcohol bifunctionality to reduce side reactions; provides temporary conformational/reactivity constraints and can be deprotected mildly back to the target functional groups |
Oxazolidinone (oxazolidin-2-one) | Oxazolidine ring bearing a carbonyl; essentially a cyclic carbamate | Classic scaffold of Evans chiral auxiliaries (asymmetric synthesis and stereocontrol); also a pharmacophore of oxazolidinone antibiotics (unrelated to catalytic ligand use) |
Oxazole (1,3-oxazole) | Aromatic heterocycle (stronger π conjugation, more planarity); electronically distinct from the “saturated/partially saturated small rings” (oxazoline/oxazolidine) | Aromatic heterocycle scaffold and electronic-effect module in drugs/materials; markedly different design logic and reactivity from oxazolines (ligand/monomer) |
Additional notes:
1. Oxazolines can be viewed as the “unsaturated analogs” of oxazolidines: both are N,O five-membered rings, with the key difference being saturation level and the resulting coordination/reactivity differences.
2. In the vast majority of research discussions or contexts, “oxazoline” by default means 2-oxazoline, especially when it appears in contexts such as “ligand fragments, BOX/PyBOX, 2-oxazoline monomers/polymerization.” If a paper discusses 3-oxazoline or other positional unsaturation, it will usually be explicitly indicated in the name or structure.
3. Oxazole is aromatic, whereas oxazoline/oxazolidine/oxazolidinone are non-aromatic N,O five-membered rings (oxazoline is partially unsaturated but non-aromatic; oxazolidine and oxazolidinone are saturated rings, with the latter being a cyclic carbamate). Oxazole is more often an aromatic scaffold/electronic module, while oxazoline/oxazolidine/oxazolidinone more often function as designable small-ring structural units (ligand fragments, protecting/temporary locking motifs, chiral auxiliaries, or pharmacophores).
III.Structural features: Why do they often improve “system controllability”?
Key structural point | Controllable variables it introduces | Why this matters for R&D controllability |
1) Fixed relative positions of N and O (typically a 1,3-relationship) | Local polarity/dipole, distribution of H-bond acceptors, solvation mode, and coordination-site geometry (which also changes with substitution, protonation state, and whether a carbonyl or acetal form is present) | Enables easier fine-tuning of solubility/interfacial behavior at comparable size; in catalysis, it also supports building stable and predictable coordination environments |
2) Geometric constraint of a five-membered ring (compact; lower conformational freedom) | Concentrates stereochemical information near the interaction site: more controllable substituent orientations and fewer accessible transition-state conformations | One structural basis for high asymmetric induction in oxazoline ligands (e.g., BOX/PyBOX): trading “designable local geometry” for a more stable selectivity window |
3) Functionalization-type differences across the family (oxazoline/oxazolidine/oxazolidinone correspond to different electronic structures and stabilities) | Choose among strategies spanning “stable scaffold ↔ reversible protection/temporary lock ↔ controllable assembly/disassembly”: oxazolidines are common as N,O-acetal protecting forms; oxazolidinones are more stable and can serve as chiral auxiliaries/pharmacophores; oxazolines are common as ligand fragments and monomer platforms | Lets you select the appropriate “tool form” by task: need temporary deactivation/handling → oxazolidine (acetal protection); need predictable stereocontrol → oxazoline ligands; need stable, reusable stereocontrol units or pharmacophore scaffolds → oxazolidinones |
Supplement:
The “systematic” nature of oxazoline ligands in asymmetric catalysis is largely due to their modularity and to the mature methodological foundation accumulated for the C2-symmetric BOX family. Chemical Reviews and its updated review articles provide comprehensive summaries of this ligand lineage.
IV.Three typical application tracks
If your goal is selectivity, go to A.
If your goal is designable polymers, go to B.
If your goal is synthetic operability / stereocontrol, or to understand pharmacophore scaffolds, go to C.
A. Asymmetric catalysis: Why are oxazoline ligands often treated as a “modular ligand toolbox”?
Oxazoline-based ligands (especially the BOX / PyBOX families) are widely used in asymmetric catalysis, typically for three reasons:
1. Predictable coordination geometry (with the “ring nitrogen” as the primary donor site)
Most BOX ligands are N,N-bidentate, chelating metals through the N atoms of two oxazoline rings. PyBOX ligands are commonly N,N,N-tridentate, with the pyridine N coordinating cooperatively with two oxazoline N donors. In these systems, the oxazoline ring oxygen is usually not the primary coordination site.
Because the identity and spatial relationship of the key donor atoms are clear, it is easier to rapidly build a relatively stable chiral coordination environment across different metal systems, and to run systematic “metal × ligand × conditions” screening and optimization.
2. Strong modularity—facilitates building “ligand structure–selectivity” relationships
Substitution on the oxazoline ring, the linking scaffold, rigidity, and steric volume can be scanned in a series using a consistent design logic—turning “trial-and-error” into a reusable workflow for structural-parameter optimization.
3. Mature symmetry strategies (C2-symmetric BOX as a classic handle)
Design concepts represented by C2-symmetric BOX are often used to reduce the number of possible transition-state types and to improve selectivity and predictability. This is also one reason why the BOX family has long served as a common “entry-level and benchmark” system.
Practical tip:
Start with BOX (C2-symmetric, N,N-bidentate) to map and benchmark your system → then expand to PyBOX (more dentate, stronger constraints) for finer tuning and broader substrate exploration. Systematic overviews can be approached via Chemical Reviews articles and their updated reviews.
B. Materials and bio-related systems: Why can 2-oxazolines form a “programmable (hydrophilic / amphiphilic) polymer” platform?
The core value of 2-oxazoline monomers is that they can often be polymerized via (quasi-)living/controlled cationic ring-opening polymerization (CROP) to give relatively well-defined poly(2-oxazoline)s (POx). This makes materials design easier to “parameterize”:
1. Key tunable parameters are explicit: molecular weight, dispersity control, block architectures (AB/ABA, etc.), side-chain chemistry (determines hydrophilic/amphiphilic/hydrophobic behavior), and end-group functionalization (enabling conjugation to ligands/dyes/drugs).
2. “Hydrophilic” is not one-size-fits-all: the hydrophilicity of POx is largely side-chain-dependent—some side chains are more hydrophilic/“stealth,” while others are more amphiphilic and better suited for self-assembly and drug-loading structures.
In drug-delivery and biomaterials literature, POx is often discussed as a potential alternative to, or complement of, PEG. Put differently: POx provides another programmable toolbox of hydrophilic/amphiphilic polymers—whether it can truly “replace” PEG depends on the specific system constraints (immune response, stability, manufacturing, regulatory pathway, etc.).
C. Synthesis and drugs: What problems do oxazolidines (temporary locking) and oxazolidinones (mature platforms) solve?
C1 | Oxazolidine-type N,O-acetals: making amino alcohols more “workable”
In protecting-group chemistry, N,O-acetals (often in the oxazolidine form) are a common strategy for 1,2- and 1,3-amino alcohols: they temporarily integrate two highly reactive sites (amine and alcohol) into a single ring structure, thereby reducing side reactions and improving selectivity and purification feasibility. When needed, the protecting motif can be removed under appropriate conditions to regenerate the original functional groups.
Reminder: Such protections are often sensitive to acids/water and related conditions. The actual stability and deprotection window is strongly context-dependent—on substrate substitution, the acetal source (aldehyde vs ketone), and the reaction environment. In practice, prioritize established conditions from closely related substrates.
C2 | Oxazolidinones: one ring connecting two mature systems (chiral auxiliaries and antibiotic scaffolds)
1. Asymmetric synthesis (the Evans chiral auxiliary system)
Evans N-acyl oxazolidinones represent a highly mature chiral-auxiliary strategy: the oxazolidinone unit is temporarily attached to the substrate, then its geometric constraint in the transition state (e.g., in aldol reactions) delivers stable, predictable stereoselectivity. After the reaction, the auxiliary is removed and can often be recovered. Its scope and trade-offs include the extra installation/removal steps and certain requirements on reaction conditions and functional-group tolerance.
2. Medicinal chemistry (oxazolidinone-class antibiotic scaffold)
Drugs represented by linezolid are explicitly classified in FDA labeling as oxazolidinone-class antibiotics; their key scaffold contains the 1,3-oxazolidin-2-one structural unit.
Note: The drug information above is provided only for understanding chemical/pharmacophore scaffolds and does not constitute any medication advice.
V.Positioning table: which class should you prioritize for a given task?
Task | Priority focus | Key checkpoints |
Improve selectivity and predictability in asymmetric reactions (quickly stabilize ee/yield) | Oxazoline chiral ligands (BOX / PyBOX / PHOX / PyOX) | Denticity and geometry (P,N / N,N / N,N,N; symmetry vs non-symmetry) → steric volume and rigidity of substituents → metal matching (whether common metal systems “accept” that denticity) → sensitivity points (effects of solvent/temperature/additives on complexation and selectivity) |
Build “programmable” hydrophilic/amphiphilic polymers or biointerfaces (anti-fouling/drug delivery/thermoresponse, etc.) | 2-oxazoline materials route (2-oxazoline monomers → POx / PEtOx) | Side chains determine hydrophilicity/hydrophobicity and responsiveness (substituent changes drive solubility/phase behavior) → polymerization controllability (MW/distribution control; block-copolymer feasibility) → end-group and functionalization strategy (need for grafting/conjugation/surface immobilization) → application constraints (stability under salts/proteins/temperature windows) |
Improve operability and route robustness of amino-alcohol intermediates (easier separation, fewer side reactions, easier scale-up) | Oxazolidine-type N,O-acetal protecting motifs (Oxazolidine) | Formation/deprotection window (acid/water sensitivity; can it be removed under mild conditions?) → functional-group compatibility (tolerance to aldehydes/ketones, alkenes, halides, reduction/oxidation) → whether conformational restriction is introduced (does “locking” affect downstream selectivity/yield?) → process operability (crystallization/extraction/column friendliness) |
Use a mature stereocontrol auxiliary, or distinguish in med-chem/literature whether “oxazolidinone” is a synthetic tool vs a drug scaffold | Oxazolidinones (Evans-type chiral auxiliaries / 2-oxazolidinone core) | First separate use cases: chiral auxiliary (stereocontrol) vs core scaffold/pharmacophore; auxiliary route: match reaction type (aldol/alkylation/Michael) + feasibility of installing/removing/recovering the auxiliary; core route: N-substitution and other functionalization entry points + impact of polarity/solubility on the system; finally: verify the condition window and selectivity/yield at small scale—avoid relying solely on “template experience.” |
VI.Product Navigation Table | Oxazoline/Oxazolidine-Related Chemicals: Quickly Locate Tables 1–4 by “Research Task / Experimental Scenario”
Research task / experimental need | Recommended table to check first | Why start here | Typical next-step linkage |
Asymmetric catalysis: need a set of chiral ligands that are “ready for direct screening” (want to quickly run ee/yield) | Table 1 Chiral ligands (PHOX / PyOX / PyBOX / BOX) | Table 1 focuses on the ligands themselves. The key differences are coordination mode (P,N / N,N / N,N,N) and the stereochemical environment created by substituents—ideal for directly building a ligand-library screening matrix. | If the reaction needs further fine-tuning of sterics/electronics → continue within Table 1 using substituted analog comparisons; if your system also involves polymer supports/immobilization → see Table 4 |
Literature precedent indicates PHOX or PyBOX; need “same-family, different substitution” benchmarks to optimize selectivity | Table 1 | Within the same scaffold, different substituents (tBu / iPr / Ph / Bn; bridge variations) more readily form structure–selectivity comparison sets. | If you need to switch strategy (move away from ligands toward chiral auxiliaries/substrate control) → Table 2 |
Complex molecule synthesis: want to use an Evans auxiliary to “stabilize” diastereoselectivity in aldol/alkylation/Michael steps | Table 2 Chiral auxiliaries & protecting frameworks (oxazolidinone / oxazolidine) | Table 2 is the auxiliary/protecting-framework route: install the auxiliary (form an imide), then perform key C–C bond formation—suited for designs requiring high dr and controllable configuration. | If you later need to materialize/polymerize the system (grafting, carriers) → Table 4; if you need crosslinking modification for end-group/carboxylic-acid systems → Table 3 |
Route design needs an amino-alcohol protection (e.g., oxazolidine), and you want to retain a further reactive handle (e.g., an aldehyde) | Table 2 | Table 2 includes entries combining protecting frameworks + reactive handles, supporting a “protect → extend → deprotect” rhythm for route control. | If you later convert protection/coupling into polymer post-modification → Table 3 (reactive side-chain monomers) or Table 4 (ready-made polymers) |
Polymer modification: you have carboxyl-terminated polymers and want to use oxazolines for chain extension/crosslinking/compatibilization (increase MW/strength/thickening) | Table 3 Bifunctional oxazolines & reactive side-chain monomers | Table 3 concentrates on bifunctional oxazolines / crosslinking-type entries—the most common “end-group reactive” entry point in engineering applications, suitable for direct chain extension/crosslinking. | If you need polymer matrices of different MW to compare rheology/film formation → Table 4 |
“Polymerize first, then post-functionalize”: need oxazoline side chains on polymers to react later with carboxylic acids/nucleophiles for grafting or crosslinking | Table 3 | Table 3 includes vinyl oxazolines and similar designs that are polymerizable + post-reactive, ideal for building post-modifiable platforms. | If you want to skip polymerization and first evaluate compatibility using ready-made POx/PEtOx → Table 4 |
Biomaterials/drug delivery/anti-fouling coatings: want to use POx/PEtOx as “PEG-like” hydrophilic polymers (first validate solubility, cytocompatibility, anti-protein adsorption) | Table 4 Monomers & polymers (POx / PEtOx) | Table 4 provides ready-made polymers (MW gradients) plus common monomer entry points—well-suited for rapid evaluation of material properties and MW dependence. | If you find you need reactive handles for crosslinking/grafting → Table 3; if you want metal-coordination functionalization → Table 1 |
You’ve decided on PEtOx but are unsure about MW: want to understand how high/medium/low MW affects viscosity, film formation, and processing window | Table 4 | Under the same CAS, Table 4 typically offers multiple MW grades (e.g., 5,000 / 50k / 200k / 500k), ideal for MW–property benchmarking. | If you want to form PEtOx networks/curable systems → Table 3; if you want ligand immobilization or metal functionalization → Table 1 |
Planning to synthesize POx via CROP: need to pick monomers (MeOx / EtOx / PrOx / BuOx / PhOx) to tune hydrophilicity/hydrophobicity and thermo-responsiveness | Table 4 | Table 4 includes common 2-substituted-2-oxazoline monomers, enabling selection based on “substituent → hydrophilicity/phase separation/LCST tendency.” | If you want to introduce post-reactive handles on the polymer → Table 3 (vinyl oxazolines); if you want metal-coordination functionality → Table 1 |
Table 1 | Chiral Ligands (PHOX / PyOX / PyBOX / BOX) for Asymmetric Catalysis and Coordination Catalysis
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product highlights & applications |
Chiral ligand | PHOX (phosphino-oxazoline) / asymmetric catalysis | 164858-78-0 | (R)-(+)-2-[2-(Diphenylphosphino)phenyl]-4-isopropyl-2-oxazoline | ≥98% | Classic PHOX (P,N) chiral ligand: commonly paired with Rh/Ir/Pd and related metals for asymmetric hydrogenation, allylic substitution, and other asymmetric catalysis; suitable as a benchmark for building and screening a “high-ee ligand library.” | |
Chiral ligand | PHOX (phosphino-oxazoline) / asymmetric catalysis | 148461-16-9 | (S)-4-tert-Butyl-2-[2-(diphenylphosphino)phenyl]-2-oxazoline | ≥97% | PHOX (P,N) chiral ligand: widely used in Rh/Ir asymmetric hydrogenation and Pd allylic substitution; the tert-butyl group can markedly change steric shielding and is a common “ligand structure–selectivity” comparison point. | |
Chiral ligand | PyOX (pyridine–oxazoline) / coordination catalysis | 117408-98-7 | (S)-4-tert-Butyl-2-(2-pyridyl)oxazoline | ≥98% (GC) | PyOX (N,N) chiral ligand: frequently used for ligand screening in coordination catalysis and asymmetric reactions with Pd/Cu/Ir and other metals; cooperative coordination of pyridine N + oxazoline N facilitates construction of a tunable stereochemical environment. | |
Chiral ligand | PyBOX (tridentate) / asymmetric catalysis | 165125-95-1 | 2,6-Bis(4,5-dihydrooxazol-2-yl)pyridine | ≥97% | PyBOX (N,N,N) tridentate ligand: commonly forms stable chelate complexes with lanthanides/transition metals; used in diverse asymmetric catalysis (additions, cyclizations, functionalizations, etc.); a classic ligand scaffold for “methodology/mechanistic” studies. | |
Chiral ligand | BOX (bis-oxazoline) / asymmetric catalysis | 131833-97-1 | (R,R)-(+)-2,2'-Isopropylidenebis(4-tert-butyl-2-oxazoline) | ≥98% | Representative iPr-bridged BOX chiral ligand: widely used in Cu/Fe/Zn and other metal systems for asymmetric catalysis (a common benchmark in ligand screening); tert-butyl substitution supports steric-environment tuning. | |
Chiral ligand | BOX (bis-oxazoline) / asymmetric catalysis | 131833-93-7 | 2,2′-Isopropylidenebis[(4S)-4-tert-butyl-2-oxazoline] | ≥98% | BOX chiral ligand (paired with the R,R enantiomer): enables rapid switching of product absolute configuration in asymmetric catalysis; commonly used in Cu/Fe/Zn ligand libraries. | |
Chiral ligand | BOX (bis-oxazoline) / asymmetric catalysis | 150529-93-4 | (+)-2,2′-Isopropylidenebis[(4R)-4-phenyl-2-oxazoline] | ≥96% | Aryl-substituted BOX chiral ligand: forms bidentate coordination with many metals; used in asymmetric additions/cyclizations, etc.; phenyl substitution is often used to increase rigidity and expand the enantioselectivity window. | |
Chiral ligand | BOX (bis-oxazoline) / asymmetric catalysis | 131457-46-0 | (S,S)-2,2'-Isopropylidenebis(4-phenyl-2-oxazoline) | ≥97% | Aryl BOX ligand (S,S): often used when pursuing higher rigidity and a broader selectivity window; forms stable chelate complexes with metals, facilitating condition screening. | |
Chiral ligand | BOX (bis-oxazoline) / asymmetric catalysis | 131833-92-6 | (S,S)-2,2'-Isopropylidenebis(4-isopropyl-2-oxazoline) | ≥95% | BOX chiral ligand (isopropyl-substituted): used to tune steric bulk/flexibility to match substrates; suitable for fine ligand-structure adjustments and comparisons (tBu/iPr/Ph). | |
Chiral ligand | BOX (bis-oxazoline) / asymmetric catalysis | 132098-54-5 | 2,2′-Methylenebis[(4S)-4-tert-butyl-2-oxazoline] | ≥96% | Methylene-bridged BOX chiral ligand: the bridge differs from isopropylidene and can significantly alter coordination geometry and selectivity; commonly used as a scaffold comparison in ligand screening. | |
Chiral ligand | BOX (bis-oxazoline) / asymmetric catalysis | 133463-88-4 | 2,2'-Bis[(4S)-4-Benzyl-2-oxazoline] | ≥98% | Benzyl-substituted BOX chiral ligand: can tune enantioselectivity through sterics and aryl interactions; commonly used for ligand screening in Cu/Ag and related systems. | |
Chiral ligand | BOX (bis-oxazoline) / asymmetric catalysis | 195433-00-2 | (4R,4'R)-2,2'-(4,6-Dibenzofurandiyl)bis[4,5-dihydro-4-phenyloxazole] | ≥95% | Representative rigid aryl-bridged BOX chiral ligand: forms bidentate coordination with Cu/Fe/Ag and others; often used for enantioselectivity screening and optimization in asymmetric cyclization/addition/oxidation and related reaction systems. |
Table 2 | Chiral Auxiliaries and Protecting Frameworks (Oxazolidinones / Oxazolidines)
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product highlights & applications |
Chiral auxiliary | Oxazolidinone (Evans auxiliary) | 102029-44-7 | (R)-4-Benzyl-2-oxazolidinone | ≥99% | Representative Evans chiral auxiliary: used in asymmetric aldol reactions, alkylations, Michael additions, etc.; achieves high diastereoselective control via formation of N-acyl oxazolidinone (imide) intermediates. | |
Chiral auxiliary | Oxazolidinone (Evans auxiliary) | 90719-32-7 | (S)-4-Benzyl-2-oxazolidinone | ≥99% | Classic enantiomer in the Evans auxiliary series: paired with the (R)-enantiomer to access products of opposite absolute configuration; commonly used as a standard starting material in asymmetric methodology development and process-route design. | |
Chiral auxiliary | Oxazolidinone (Evans auxiliary) | 17016-83-0 | (S)-(-)-4-Isopropyl-2-oxazolidinone | ≥98% | Common Evans-auxiliary variant: after building the N-acyl oxazolidinone, enables highly selective C–C bond constructions (aldol/alkylation, etc.); the isopropyl group provides a distinct steric “tuning point.” | |
Chiral auxiliary | Oxazolidinone (Evans auxiliary) | 99395-88-7 | (S)-(+)-4-Phenyl-2-oxazolidinone | ≥98% | Aryl-substituted Evans auxiliary: often used to enhance/shift diastereoselectivity; well-suited for auxiliary benchmarking such as “benzyl vs phenyl vs isopropyl.” | |
Core scaffold / solvent | 2-Oxazolidinone | 497-25-6 | 2-Oxazolidinone | ≥99% | Fundamental cyclic carbamate scaffold: can serve as a high-boiling polar solvent/reaction medium (strong solubility for salts and polar substrates); also a common starting material for oxazolidinone derivatization and for building ethanolamine-containing structures. | |
Protecting group / chiral building block | 1,3-Oxazolidine (Oxazolidine) | 102308-32-7 | (S)-(-)-3-(tert-Butoxycarbonyl)-4-formyl-2,2-dimethyl-1,3-oxazolidine | ≥95% | “Amino alcohol → oxazolidine” protecting framework plus an aldehyde reactive handle: commonly used in routes to chiral amino aldehydes/amino alcohol derivatives (e.g., reductive amination, additions / carbon-chain extension), enabling deprotection in later steps to regenerate the amino alcohol. |
Table 3 | Bifunctional Oxazolines and Reactive Side-Chain Monomers (Chain Extension / Crosslinking / Post-Modification)
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product highlights & applications |
Bifunctional oxazoline | chain extender / crosslinker / coordination ligand | 36697-72-0 | 2,2'-Bis(2-oxazoline) | ≥97% | Classic bis-oxazoline bifunctional reagent: widely used for chain extension/thickening/crosslinking and compatibilization of carboxy-terminated polymers; also useful in metal coordination and as a methodology benchmark. | |
Bifunctional oxazoline | chain extender / crosslinker / coordination ligand | 34052-90-9 | 1,3-Bis(4,5-dihydro-2-oxazolyl)benzene | ≥98% | Aryl-bridged bis-oxazoline: can serve as a bi-/multidentate coordination scaffold for metal complexation; also commonly used for polymer chain extension/crosslinking via reaction with carboxy end groups (introducing stable amide linkages / end-group modification). | |
Functional monomer | vinyl oxazoline (post-modification / crosslinking) | 10471-78-0 | 2-Isopropenyl-2-oxazoline | ≥98% | Combines a polymerizable vinyl group with a reactive oxazoline side group: enables radical polymerization to introduce pendant oxazoline groups, followed by ring-opening reactions with carboxylic acids or other nucleophiles for polymer post-functionalization, grafting, and crosslink-curing. |
Table 4 | Polymerization Monomers and Polymers (2-Oxazoline CROP Monomers / Finished POx and PEtOx Polymers)
Category | CAS No. | Aladdin Cat. No. | Name | Specification / Purity | Product highlights & applications |
Polymerization monomer | 2-substituted-2-oxazoline (CROP monomer) | 1120-64-5 | 2-Methyl-2-oxazoline | ≥98% (GC) | Core monomer for hydrophilic poly(2-methyl-2-oxazoline): widely used to build “PEG-like” hydrophilic segments, protein/drug conjugation carriers, and water-soluble copolymer systems. | |
Polymerization monomer | 2-substituted-2-oxazoline (CROP monomer) | 10431-98-8 | 2-Ethyl-2-oxazoline | ≥98% (GC) | Key monomer for PEtOx (poly(2-ethyl-2-oxazoline)): high water solubility; often used as an entry point for PEG-like alternative material routes (biomaterials, anti-fouling coatings, drug-delivery copolymers). | |
Polymerization monomer | 2-substituted-2-oxazoline (CROP monomer) | 4694-80-8 | 2-Propyl-2-oxazoline | ≥98% | CROP monomer: used to synthesize polymers such as poly(2-propyl-2-oxazoline); commonly applied in amphiphilic copolymers, tuning thermo-responsive windows, and formulation screening for drug-delivery carriers. | |
Polymerization monomer | 2-substituted-2-oxazoline (CROP monomer) | 27031-10-3 | 2-n-Butyl-2-oxazoline | — | Common CROP monomer: used to prepare more hydrophobic/amphiphilic POx segments; co-polymerized with hydrophilic blocks to build micelles, drug-loading systems, or surface-modification polymers. | |
Polymerization monomer / building block | aryl-2-oxazoline | 7127-19-7 | 2-Phenyl-2-oxazoline | ≥99% | Aryl-substituted oxazoline: can be used as a CROP monomer to prepare more hydrophobic, higher-Tg POx segments; also commonly used as a synthetic building block / coordination-scaffold entry featuring an oxazoline motif. | |
Polymer | poly(2-oxazoline) (hydrophilic / PEG-like) | 161358-46-9 | ULTROXA® Poly(2-methyl-2-oxazoline) (n=approx. 100) | — | Hydrophilic POx (n≈100): often used for anti-fouling surface modification, protein/drug compatibility evaluation, and as a water-soluble polymer benchmark; a common option as a PEG-like hydrophilic-segment alternative. | |
Polymer | poly(2-oxazoline) (thermo-responsive / amphiphilic) | 941228-32-6 | ULTROXA® Poly(2-propyl-2-oxazoline) (n=approx. 100) | — | Pre-made POx (n≈100): commonly used for amphiphilic assembly, exploring thermo-responsive behavior, and drug-loaded micelle/nanoparticle formulations; suitable for rapid “fixed DP” material benchmarking. | |
Polymer | PEtOx (low MW / usable as a grafting segment) | 25805-17-8 | Poly(2-ethyl-2-oxazoline) | Mw 5000 | Low-MW PEtOx: commonly used for surface modification/grafting segments, blend solubilization, or as a polymer additive; suitable for “short hydrophilic segment” benchmarking and pre-coupling evaluation. | |
Polymer | PEtOx (hydrophilic / MW benchmark) | 25805-17-8 | Poly(2-ethyl-2-oxazoline) | average Mw ~50,000, PDI 3–4 | Medium-MW PEtOx: commonly used for solution-property, adsorption/anti-fouling, and bio-compatibility benchmarking; convenient for “molecular weight–property window” gradient experiments. | |
Polymer | PEtOx (hydrophilic / polymer matrix) | 25805-17-8 | Poly(2-ethyl-2-oxazoline) | MW ≈ 200,000 | High-MW PEtOx: suitable as a water-soluble polymer matrix (thickening, film formation, coatings/hydrogel network precursors); used to evaluate MW effects on viscosity, film formation, and biocompatibility. | |
Polymer | PEtOx (very high MW / film-forming & thickening) | 25805-17-8 | Poly(2-ethyl-2-oxazoline) (PEOX) | average Mw ~500,000, PDI 3–4 | Ultra-high-MW PEtOx: more oriented toward thickening/film formation and network construction (coatings, hydrogels, rheology modification); suitable for assessing high-MW impacts on processing window and mechanical/rheological behavior. |
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