Enzymatic Synthesis Of New Antiarrhythmic Drug: CVT-510

The dissertation reviewed how to make chiral drugs, especially how to prepare the drugs by enzymes and also discussed the mechanism of enzymatic synthesis of nucleotide analogues. The advantages and disadvantages of enzyme catalysis in organic media and factors which affect the efficiency of biocatalysis in organic media were also discussed. The pharmacology, clinic researches and chemical synthesis of CTV-510 were introduced. Most importantly, the significance to prepare the new antiarrhythmic drug CVT-510 using enzyme was proposed.CVT-510 was developed by CV Therapeutics in USA. Clinical trials have shown that CVT-510 is effective in terminating paroxysmal supraventricular tachycarelia (PSVT) and eliminating many of the undesirable adverse effects of adenosine. CVT-510 is also being explored as a potential agent for controlling the ventricular rate of atrial fibrillation and flutter. To synthesize CVT-510, the key intermediates are 3-(S)-amino-tetrahydrofuran (intermediate 1) and 6-chlropurine riboside (intermediate 2).To obtain high yield and enantioselectivity of 3-(S)-aminotetrahydro-furan, N-benzyloxycarbonyl-3-aminoterhydrofuran was used to give 63% comparing to the reference yield (51%). Then 3-(S)-aminotetrahydrofuran was made by using enzymatic catalysis in organic media. Papain was selected by researches from 8 different enzymes including papain, lipases and subtilisin. The catalytic reactions were also studied in different solvents and temperatures with papain. The reaction yield and e.e. value reached more than 25% and 15% respectively if tetrahydrofuran or butanol as themediaat35°C-40°C.To obtain high yield and enantioselectivity of 6-chlropurine riboside, Lactobacillus heheticus (ATCC8018) or crude N-deoxyribosyl transferases were used to catalyze base exchange from guanosine riboside and 6-chlropurine. The opitmal conditions for ultrasonic staving on enzymatic reaction were studied to give following conditions: ultrasonic convertor power (360W);concentration of bacteria (20%);total time (10 min);pause 6s and keep 4s). The optimal conditions for the enzymatic reaction were finally obtained through our researches: guanosine riboside (30 mmol/L);6-chlropurine (10 mmol/L);wet whole cells (8%—10%);pH 6.0, incubatingtime (24 h);reaction temperature (40°C);shaking speed (100~150 r/min).With this new biological system, only one step needed to give more than 50% conversion yield comparing to four steps and 28% by chemical methods.Hua-wei FAN (Apply Chemistry) Supervised by Li-min ZHU Dr. Prof.