(S)-2-{[(((1R,2R)-2-(allyloxy)cyclopentyl)oxy)carbonyl]amino}-3,3-dimethylbutanoic acid

China [CN]

Physical State: A white to off-white crystalline powder at room temperature, odorless, slightly hygroscopic (due to hydrogen bonding between the carboxyl group and the carbamate), requiring conventional sealing and moisture protection;

Melting Point: 105~110℃ (melting range ≤5℃; a melting range exceeding this indicates the presence of diastereoisomers/process impurities), a core indicator for initial assessment of chiral purity;

Specific Rotation: [α]D25 = -18° to -22° (c=1.0, methanol), the sole indicator for determining chiral configuration; deviation from this range indicates the presence of chiral racemates/isomeric impurities;

Solubility: Slightly soluble in water (solubility at 25℃ ≈ 2.5 g/L, pH 7.0), readily soluble in methanol, ethanol, ethyl acetate, tetrahydrofuran (THF), DMF, and DMSO, slightly soluble in dichloromethane and toluene, insoluble in n-hexane and petroleum ether (medium polarity, suitable for organic phase peptide/drug synthesis);

Dissociation Constant: pKa ≈ 3.8 (carboxyl group, strongly acidic), pKa ≈ 10.5 (carbamate N-H, weakly acidic), aqueous solution is weakly acidic (pH 3.5~4.5), reacts with bases (NaOH/K2CO3) to form carboxylate salts, significantly increasing water solubility;

Stability:

Stable for ≥24 months when stored dry and sealed at room temperature (15~30℃), without degradation;

Stable to acids (pH 2~7) and conventional oxidizing agents; under alkaline conditions (pH > 9), the carbamate bond is slowly hydrolyzed, releasing (S)-tert-leucine;

Allyloxy group characteristics: Can be selectively removed under the action of Pd(0) catalysts (such as Pd(PPh3)4) (neutral/weakly acidic conditions), without side reactions of other functional groups;

Avoid high temperatures (>120℃): At high temperatures, intramolecular condensation occurs between the carboxyl group and the carbamate, generating lactam impurities.