Biological Active Esters of the Isovaleric Acid

Abstract

<p>Hydroalkoxycarbonylation of olefins with carbon monoxide and alcohols under condition of homogeneous –catalysis with transition metal complexes allows facile one-step synthesis of practically <br /> useful carbon acid esters. Many of them have biological activity and are constituents of drugs or valuable intermediate products in drug synthesis. Hydroalkoxycarbonylation of isobutylene with carbon monoxide and alcohols in the presence of catalytic system Pd(PPh<sub>3</sub>)<sub>4</sub>-PPh<sub>3</sub>-TsOH was applied for preparing of biological active isovaleric acid esters: <em>1</em>-menthylisovalerate (main active component of the spasmolytic medicine “Validolum”), ethylisovalerate (intermediate product for obtaining sedative and spasmolytic medicines “Ethyl ester of <em>α</em>-bromisovaleric acid” and “Corvalolum”), cyclohexylisovalerate (bactericide activity) and benzylisovalerate (bactericide and antifungus activity). Hydroalkoxycarbonylation reaction of isobutylene with carbon monoxide and alcohols (ethanol, cyclohexanol, l-menthol, benzyl alcohol) in the presence Pd(PPh<sub>3</sub>)<sub>4</sub>-PPh<sub>3</sub>-TsOH system carried out at conditions: temperature 100 °C; CO pressure 2.0 MPa; reaction time 4 h; reactants and catalyst components ratio [alcohol]:[isobutylene]:[Pd(PPh<sub>3</sub>)<sub>4</sub>]:[PPh<sub>3</sub>]:[TsOH] = 435:550:1:3:12. The yields of the products were 71-95% (on converted alcohols). The selectivity in linear reaction products was 100%. Such a high regioselectivity is apparently provided both by the structure of the starting alkene (isobutylene) and by the reaction mechanism. The most probable is a hydride mechanism. Due to the more advanced technology of production the Medicines will have better qualitative characteristics. The cost of production of the Medicines with the use of new technologies is 2-3 times lower as compared to the medicines produced by existing at the present traditional technologies.</p>