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:
Aug. 28, 1990
Filed:
Jul. 27, 1988
Marcus Brackeen, Durham, NC (US);
Harry R Howard, Jr, Hartford, CT (US);
Pfizer Inc., New York, NY (US);
Abstract
A novel three-step process for resolving a racemic spiro-hydantoin compound into its optical antipodes is disclosed, which involves (1) reacting said racemic compound with an optically-active asymmetric isocyanate of the formula RNCO, wherein R is (S)- or (R)-1-phenylethyl or (S) or (R)-1-(1-naphthyl)ethyl, to form the corresponding diastereomeric uredio compound; (2) separating the resulting diastereomeric mixture into its component parts, and (3) thereafter converting the separated ureido diastereomers obtained in step (b) to the corresponding asymmetric hydantoin compounds by treatment with an alkali metal lower alkoxide (C.sub.1 -C.sub.4), followed by acidification, whereupon the desired optical isomer is obtained. The final products so obtained, such as (4S)-(+)-6-fluoro-2,3-dihydro-spiro[4H-1-benzopyran-4,4'-imidazolidine]-2' , 5'-dione (sorbinil) and (5'S)-3'-chloro-5', 6', 7', 8'-tetra-hydro-spiro[imidazolidine-4,5'-quinoline]-2,5-dione, are known to be useful in preventing or alleviating certain chronic diabetic complications. The aforementioned diastereomeric uredio intermediates are novel compounds.