The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 19, 2000
Filed:
Dec. 03, 1998
Mahavir Prashad, Montville, NJ (US);
Bin Hu, North Plainfield, NJ (US);
Novartis AG, Basel, CH;
Abstract
A process for preparing the d-threo isomer of methylphenidate hydrochloride comprising converting d,l-threo methylphenidate hydrochloride to the free base form in a first step, resolving the free base prepared in the first step with (R)-(-)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate to obtain the phosphate salt enriched with the d-threo isomer of methylphenidate in a second step, basifying the phosphate salt to obtain the free base form of the d-threo isomer of methylphenidate in a third step, converting the free base to the hydrochloride salt form of the d-threo isomer of methylphenidate in high optical purity in a fourth step, and recrystallizing the hydrochloride salt form to obtain the desired d-threo isomer in a higher optical purity. An alternative embodiment relates to the preparation of the d-threo isomer of methylphenidate hydrochloride utilizing the hydrochloride salt form of the racemic mixture of threo-methylphenidate directly.