(2S,3R)-3-Methoxy-2-((Methoxycarbonyl)aMino)butanoic acid

China [CN]

Physical State: At room temperature, it is a white to off-white crystalline powder, odorless, with moderate hygroscopicity (due to the synergistic effect of hydrogen bonding between carboxyl and carbamate groups), and requires sealed, moisture-proof storage;

Melting Point: 118~122℃ (melting range ≤4℃; a melting range exceeding this indicates the presence of diastereoisomers/raw material impurities), a core indicator for initial assessment of chiral purity and overall purity;

Specific Rotation: [α]D25​=−28° −32° (c=1.0, methanol), the unique determinant of the (2S,3R) configuration; deviation from this value indicates chiral racemization/diastereoisomerism;

Solubility: Easily soluble in water (solubility at 25℃ ≈ 42g/L, pH 7.0), easily soluble in methanol, ethanol, acetone, DMF, DMSO, slightly soluble in ethyl acetate, tetrahydrofuran, insoluble in dichloromethane, n-hexane, toluene (polar characteristics suitable for biphasic reactions in aqueous/organic phases);

Dissociation Constant: pKa ≈ 3.6 (carboxyl group, strongly acidic), pKa ≈ 10.8 (carbamate N-H, weakly acidic), aqueous solution is weakly acidic (pH 3.8~4.5), and its water solubility is significantly increased after salt formation with bases (NaOH/K2CO3) (sodium salt solubility ≈ 180g/L);

Stability:

Stable for ≥24 months under dry, sealed storage at room temperature (15~30℃) with no degradation;

Stable to acids (pH 2~7), conventional oxidizing/reducing agents; under alkaline conditions (pH>9, such as NaOH/ammonia water), a double reaction can occur: carboxyl group salt formation and hydrolysis of the Moc protecting group ester bond, releasing a free amino group;

Chiral Stability: Under neutral/weakly acidic conditions/≤80℃, the two chiral centers do not racemize, suitable for most drug synthesis reaction conditions;

Moc Protecting Group Characteristics: In concentrated hydrochloric acid/... Trifluoroacetic acid (TFA) can be quantitatively removed at room temperature without side reactions with other functional groups, making it a selective protecting group for amino groups via acidolysis;

Avoid high temperatures (>150℃): Intramolecular condensation occurs at high temperatures, generating oxazolidinone heterocyclic impurities.