Process for preparing the d-threo isomer of methylphenidate hydrochloride
US6100401A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 20, 1998 |
| Grant date | Aug 8, 2000 |
| Priority date | — |
| Expiry date | Apr 20, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D211/34
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for preparing the d-threo isomer of methylphenidate hydrochloride comprising resolving the racemic mixture of threo methylphenidate hydrochloride with dibenzoyl-D-tartaric acid to obtain a dibenzoyl-D-tartrate salt enriched with the d-threo isomer of methylphenidate in a first step, basifying the tartrate salt to obtain the free base form of the d-threo isomer of methylphenidate in a second step, converting the free base to the hydrochloride salt form of the d-threo isomer of methylphenidate in high optical purity in a third step, and recrystallizing the hydrochloride salt form to obtain the desired d-threo isomer in a higher optical purity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.