Enantiomeric Separation Of The Key Intermediate Of Nebivolol Using Preparative Chromatography

Nebivolol is the third generation of?₁ receptor blocker.Because of the significant effect of treating hypertension,it has broad application prospects.It was first marketed in Germany in 1997,in Britain in 1998 and approved by the Food and Drug Administration?FDA?in 2007 for the treatment of mild to moderate hypertension.Nebivolol is still in the pre-clinical research stage in China.Although there are some experimental data to confirm its effectiveness and safety,it is still a long way from being listed.There are 4chiral centers in the nebivolol molecule and the clinical use is the equal mixture of?R,S,S,S?-enantiomers and?S,R,R,R?-enantiomers.At present,one of the most important industrial synthetic routes of nebivolol is the synthesis of chromane-2-carboxylic acid developed by Janssen pharmaceutica.In this synthesis method,6-fluoro-3,4-dihydro-2H-1-benzopyran-2-formic acid is the key intermediate,and its chiral resolution and purity controlling are difficult.The existing chiral resolution methods domestic and foreign mainly focus on the chemical reaction method by chiral reagents,and the reagents used are either expensive,or toxic.The chromatographic resolution has not been reported yet.In this study,two preparative chromatographic methods were used to separate the racemate,and the separation schemes were established can meet the needs of clinical research in China.The research work is as follows:1.Analytical HPLC?high performance liquid chromatography?method has been developed for the enantioseparation of the racemate.Several chiral stationary phases and mobile phases were screed,and then the best combination was established.The influence of modifier content,flowrate and temperature on enantiomeric separation was investigated,and the separation parameters were determined.The stability,repeatability and sample loading of the experiment was tested,and the separation scheme was established.Under this condition,the enantiomers resolution was 3.50.2.Preparative HPLC method has been developed.Based on the linear amplification theory,the analytical separation scheme was scaled up theoretically.According to the equipment condition,the results of the calculation were further optimized,then the preparative condition was determined.The column diameter,particle size,injection mode and maximum efficiency were also investigated.Under this method,10 grams of racemate were separated.The productive efficiency was 108 g/d,the optical purity was more than 98.5%,and the yield was 87.0%.3.Analytical SFC?supercritical fluid chromatography?method has been developed for the enantiomeric separation of the racemate.Several chiral stationary phases and mobile phases were screed,and then the best combination was established.The influence of modifier content,flowrate,temperature,backpressure on the separation was investigated,and the best parameters were determined.The stability,repeatability and sample loading of the experiment was tested,and the separation scheme was established.Under this method,the enantiomers resolution was 4.20.4.Preparative SFC method has been developed.Based on the linear amplification theory and isocratic systems,the analytical separation scheme was scaled up theoretically.According to the equipment condition,the result of the calculation was further optimized,then the preparative condition was determined.The column diameter,particle size,injection mode and maximum efficiency were also investigated.Under this method,20 grams of racemate were separated.The productive efficiency was 166 g/d,the optical purity was more than 98.0%,and the yield was 88.0%.