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| Author(s): |
Joel Savi dos Reis
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2013-12-09 |
| Examining board members: |
Cassius Vinicius Stevani;
Alvaro Takeo Omori;
Alcindo Aparecido dos Santos;
Luiz Fernando da Silva Junior;
Rodrigo Octavio Mendonça Alves de Souza
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| Advisor: | Leandro Helgueira de Andrade |
| Abstract | |
In this work, the kinetic resolution of β-borylated carboxylic esters via lipase-catalyzed hydrolysis and transesterification reactions was evaluated. Esteres with different carbon chains were synthesized. The enantioselective hydrolysis catalyzed by CAL-B furnished the corresponding β-borylated carboxylic acid with reasonable enantiomeric excess (ee 62%), while both methyl and ethyl β-borylated carboxylic esters were recovered with excellent enantiomeric purity (ee>99%). The enantioselective transesterification reaction of β-borylated carboxylic esters and several alcohols, catalyzed by CAL-B, only indicated a high selectivity when ethanol and methyl-(β-pinacolylboronate)-butanoate were used as substrates, which gave the enantioenriched ethyl-(β-pinacolylboronate)-butanoate (ee >99%). However, esters with longer carbon chains or steric hindrance at the carboxyl group did not undergo the desired reactions, even at high temperatures. Additionally, the asymmetric reductive amination ω-transaminase catalyzed of boron-containing (acid, ester or potassium trifluoroborate) prochiral ketones was investigated. After the syntheses of aromatic and aliphatic ketones, the best results of biotransformation were obtained with (R)-selective ω-transaminases from Arthrobacter sp. and Aspergillus terreus and (S)-selective one from Chromobacterium violaceum. Under the optimized conditions, high conversions (94%) with perfect enantioselectivities (ee >99%) were found, providing a new access to (R) or (S) boron-containing amines under mild reaction conditions. (AU) | |
| FAPESP's process: | 09/17919-1 - Evaluation of lipases, transaminases and enoato reductases as catalysts in synthesis of chiral organoboron compounds. |
| Grantee: | Joel Savi dos Reis |
| Support Opportunities: | Scholarships in Brazil - Doctorate |