Heterogeneous synthesis of azepinones from esters
US5250680A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 2, 1992 |
| Grant date | Oct 5, 1993 |
| Priority date | — |
| Expiry date | Sep 2, 2012 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D281/10
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
An amino-acid ester compound can be cyclized into a cyclic amido-carbonyl compound by contacting the amino-acid ester compound in a liquid medium with a heterogeneous acidic ion-exchange substance. For example, 2-hydroxy-3-(2-aminophenylthio)-3-(4-methoxyphenyl)propionic acid, methyl ester, threo form, can be cyclized in an aqueous mixture into cis-2-(4-methoxyphenyl)-3-hydroxy-2,3-dihydro-1,5-benzothiazepin-4(5H)-one by employing a sulfonated polystyrene-divinylbenzene ion-exchange resin in its acid form, e.g., Dowex.RTM. 50X4-400. at yields exceeding 85 percent of theory, and the product can be used to make diltiazem hydrochloride.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.