Orforglipron Intermediate M-3

II. Physical and Quality Control Parameters

Appearance: White to off-white crystalline powder; impurity content affects powder crystal form and flowability.

Solubility: Easily soluble in DCM, THF, and DMF; slightly soluble in n-hexane, water, and diethyl ether; purification is typically achieved through column chromatography or ethyl acetate/n-hexane recrystallization.

Stability: Store in a sealed container, protected from light, and in a dry environment below 25℃, avoiding high temperatures, humidity, and strong alkaline conditions; the indole N-H is easily protonated, and the Evans auxiliary is sensitive to strong acids and bases, requiring protection against hydrolysis and racemization; shelf life is approximately 12 months.

Key Quality Control Indicators

Chemical Purity: ≥99.0% (HPLC area normalization method)

Chiral Purity: ≥99.0% ee (Chiral HPLC/SFC)

Moisture Content: ≤0.5% (Karl Fischer method)

Heavy Metals: ≤10 ppm (ICP-MS)

III. Synthesis Route and Process Highlights

Synthesis Route: Using 4-bromoindole as the starting material, acylation produces an α,β-unsaturated ketone, which is then condensed with the (S)-Evans oxazolidinone derivative under alkaline conditions to produce M-3, providing a chiral precursor for the subsequent asymmetric 1,4-allylic alkylation reaction of M-4.

Process Key Points

Chiral Induction: Using the (S)-Evans auxiliary, controlling the reaction temperature (-10℃~0℃) and the amount of base used to reduce racemization caused by deprotonation of the indole N-H.

Impurity Control: Removing diastereomeric impurities through recrystallization to ensure M-3 chiral purity ≥99.0% ee, preventing impurity transfer to M-4.

Post-treatment: After the reaction, quench with citric acid, extract with ethyl acetate, dry with anhydrous sodium sulfate, concentrate under reduced pressure, and then recrystallize; yield is approximately 70%-78% (laboratory process). IV. Uses and Application Scenarios

Core Use: Used in the preclinical and commercial production of Oflurgluron API synthesis, serving as a direct precursor to M-4.  It generates M-4 through an asymmetric 1,4-allylic alkylation reaction and is one of the core sources for controlling the chiral purity of the final product.

Application Scenarios: Suitable for large-scale production under cGMP conditions, requiring quality control processes such as chiral chromatography detection and ICP-MS heavy metal screening to ensure that diastereomeric impurities are not carried over to subsequent intermediates.