Top 10 Manufacturers of Pharmaceutical Intermediate CAS No. 90357-51-0 in 2025

Understanding (2R,3S)-N-tert-Butoxycarbonyl-3-phenylisoserine (CAS No. 90357-51-0)

CAS No. 90357-51-0, known as (2R,3S)-N-Boc-3-phenylisoserine, is a Boc-protected chiral intermediate used primarily in the synthesis of Docetaxel (Taxotere), one of the most widely used chemotherapy agents in the world. This compound is the N-Boc derivative of 3-phenylisoserine, designed to improve chemical stability, solubility, and handling during multi-step synthesis.

Docetaxel is used to treat various cancers including breast, lung, prostate, and gastric cancers, making intermediates like this one highly sought after in the oncology supply chain.

Importance of CAS No. 90357-51-0 in Pharmaceutical Synthesis

Key Intermediate for Docetaxel (Taxotere)

This compound forms the side chain of Docetaxel and is essential for the drug’s activity in disrupting microtubule dynamics in cancer cells.

Protecting Group Enhances Process Control

The Boc group on the amine prevents undesired side reactions and improves purity and yield in large-scale synthesis.

Required for Enantiomeric Precision

The (2R,3S) stereochemistry ensures pharmacological efficacy and is required for regulatory approval of final APIs.

Widely Used in GMP Oncology Pipelines

As an advanced intermediate, it is routinely manufactured under GMP standards for final stage API production.

Critical for Semi-Synthetic Production

Docetaxel is produced semi-synthetically from natural precursors (like 10-DAB), with CAS 90357-51-0 as a key coupling partner.

Top 10 Manufacturers of CAS No. 90357-51-0

1. Lonza Group

• Location: Basel, Switzerland

• Overview: Lonza produces high-purity chiral intermediates for oncology APIs. Their capacity and expertise in taxane synthesis make them a preferred partner.

• Specialty: Chiral process development and regulatory support for cancer therapies.

2. Bachem AG

• Location: Bubendorf, Switzerland

• Overview: Bachem manufactures Boc-protected amino acid derivatives like CAS 90357-51-0 for taxane-based drug synthesis.

• Specialty: Peptide-grade and taxane-grade chiral intermediates.

3. Eastfine

• Location: Changzhou City, Jiangsu Province, China

• Overview: Eastfine supplies pharmaceutical intermediates such as CAS 90357-51-0 with high enantiomeric purity, strict quality control, and full export documentation.

• Specialty: Oncology-grade chiral building blocks at globally competitive prices.

4. Almac Group

• Location: Craigavon, Northern Ireland

• Overview: Almac specializes in chiral synthesis for clinical and commercial oncology APIs, offering scalable supply of Docetaxel intermediates.

• Specialty: Custom synthesis of taxane building blocks with integrated analytical validation.

5. CordenPharma

• Location: Plankstadt, Germany

• Overview: CordenPharma provides advanced intermediate manufacturing services for taxanes, including Boc-protected chiral amino acids.

• Specialty: Oncology-focused CDMO with strong regulatory track record.

6. Olon S.p.A.

• Location: Milan, Italy

• Overview: Olon manufactures key intermediates for chemotherapeutics, including semi-synthetic steps of Docetaxel production.

• Specialty: GMP manufacturing of side-chain intermediates for cytotoxic APIs.

7. Carbogen Amcis (Dishman Group)

• Location: Bubendorf, Switzerland

• Overview: Carbogen Amcis delivers custom synthesis of high-potency intermediates including CAS 90357-51-0 for global cancer drug manufacturers.

• Specialty: Complex cytotoxic intermediates with containment capabilities.

8. Pharmaron (UK Operations)

• Location: Hoddesdon, UK

• Overview: Pharmaron’s UK sites focus on GMP synthesis of oncology intermediates, offering fast turnaround on custom chiral molecules.

• Specialty: Route scouting and late-phase taxane synthesis.

9. Enzymaster Life Sciences

• Location: Düsseldorf, Germany

• Overview: Specializing in biocatalytic production of chiral intermediates, Enzymaster produces CAS 90357-51-0 with high ee via green synthesis routes.

• Specialty: Eco-friendly asymmetric synthesis using enzyme technology.

10. Seqens Group

• Location: Ecully, France

• Overview: Seqens develops and supplies Boc-protected amino acid intermediates for anti-cancer agents, with strong regulatory and analytical support.

• Specialty: Taxane-side chain expertise and scalable GMP production.

Trends in the Pharmaceutical Intermediates Market

Growing Global Demand for Oncology APIs

Cancer continues to be a top priority for drug development, driving consistent demand for advanced intermediates like CAS 90357-51-0.

Emphasis on Chiral Purity and Green Chemistry

Manufacturers are investing in enantioselective synthesis and biocatalytic approaches to reduce waste and enhance stereochemical control.

Taxane API Optimization

New process developments focus on improving yield, stability, and cost-efficiency in Docetaxel production, increasing reliance on optimized intermediates.

CDMO Partnerships for Scale and Compliance

More pharmaceutical firms are partnering with specialized CDMOs for scalable, GMP-compliant manufacturing of late-stage intermediates.

Shift Toward Semi-Synthetic Efficiency

Semi-synthetic taxanes remain the gold standard in chemotherapy, making protected intermediates like CAS 90357-51-0 crucial for high-yield, cost-effective synthesis.

Conclusion

CAS No. 90357-51-0, or (2R,3S)-N-tert-Butoxycarbonyl-3-phenylisoserine, is a pivotal intermediate in the production of Docetaxel, one of the world’s most widely used chemotherapy drugs. With its Boc protection, precise stereochemistry, and global demand, it stands at the center of modern oncology drug synthesis.

Manufacturers like Lonza, Bachem, and Eastfine are ensuring a stable, high-quality supply of this compound to meet the growing global need for effective cancer treatments.