Chemoenzymatic synthesis of (S)-Pindolol using lipases

The present work refers to the development of a biocatalytic process of the synthesis of the (S)-Pindolol, a drug used as a beta-blocker in the treatment of hypertension and cardiac arrhythmia. Moreover, this drug is an antagonist of the auto receptor 5-HT1AÂÂ, that favours the combination between medications of the selective serotonin reuptake inhibitors group (SSRIÂs), which can accelerate or increase the therapeutic efficacy of the antidepressants. The initial strategy in the process development includes, as the first step, the enzymatic kinetic resolution of a mixture of the rac - acetato de 1 - (clorometil)-2-(1H-indol-4-iloxi)etila, in the presence of the Pseudomonas fluorescens lÃpase, for obtainment of c = 50%; ee = 94% and E = 115, after 24h. The second step involved the purification and enzymatic hydrolysis of the enatiomerically pure compound acetato de (R)-acetato de 1-(clorometil)-2-(1H-indol-4-iloxi)etila, which served as substrate for the Candida rugosa lipase for production of the enantiomerically pure alcohol (R)-1-cloro-3-(1H-indol-4-iloxi)-2-propanol. From the perspective of the Green Chemistry precepts and sustainability, it was investigated the enzymatic immobilization by covalent bond formation of the enzymatic biocatalysts of the C. rugosa and P. fluorescens lipases. The utilization of the solid supports to enzyme immobilization has many advantages, such as the recovery of the biocatalyst from the reaction medium to be reutilized, limitation of the conformational variations, stability to variation of the reaction medium as the pH variation and temperature variation. The support studied in this work was the functionalized nanosilica by ATPES and glutaraldehyde. The results of the kinetic resolution of the rac - acetato de 1 - (clorometil)-2-(1H-indol-4-iloxi)etila by immobilized enzymes of the P. fluorescens were c = 47%; ee = 97% and E = 150; 12h in 10 cicles of reuse with 97% of ee. While the asymmetric hydrolysis of the (R)-acetato de 1-(clorometil)-2-(1H-indol-4-iloxi) de etila resulted in total substrate consumption for the interval of 12h of reaction and 10 cicles of the reuse. The enantiomerically pure compound (R)-1-cloro-3-(1H-indol-4-iloxi)-2-propanol was purified and submited to the reaction in the presence of the ethanol and excesso f isopropilamine. A white solid, caracterized as (S)-Pindolol, was obtained with 66% of yield.