Enantioselective enzymatic acylation of 1-(3′-bromophenyl)ethylamine

The enzymatic resolution of 1‐(4‐chlorophenyl)ethylamine by Novozym 435 to prepare a novel triazolopyrimidine herbicide

“…The other tested solvents afforded moderate conversions (41.5% to 56.4%), and the best performance was obtained in methyl tert ‐butyl ether (MTBE), with the highest E value being 7.8 and the conversion being 53.9%. Similar results were obtain in the enantioselective acylation of 2‐phenylcycloalkanamines and 1‐(3′‐bromophenyl)‐ethylamine, and MTBE seemed to be an excellent choice as a solvent in the lipase‐catalyzed kinetic resolution of chiral amines. Finally, MTBE was selected as the optimum solvent for the following tests.…”

“…Isopropenyl acetate also displayed good results, with a conversion of 54% and an E value of 7.8, but the isopropenyl acetate reaction had poor reproducibility. According to Gill's observation, extensive (up to 60%) by‐product was formed with certain batches of isopropenyl acetate . Miranda et al also found that an imine derivative formed between the free amine and propanone (derived from the isopropenyl ester) .…”

“…According to Gill's observation, extensive (up to 60%) by-product was formed with certain batches of isopropenyl acetate. 18 Miranda et al also found that an imine derivative formed between the free amine and propanone (derived from the isopropenyl ester). 21 Ethyl methoxyacetate, which is less reactive than isopropenyl acetate but much more reactive than simple esters, afforded a high conversion (52.9%) and moderate enantioselectivity (E = 5.6).…”

Lipase-catalyzed synthesis of the chiral tetrahydroisoquinoline (R)-salsolinol

“…The polar solvent isopropyl alcohol can destroy these hydrogen bonds. 30 The catalytic capacity of the immobilized enzyme is essentially the same in medium polar solvents similar to ether, including methyl tert-butyl ether, isopropyl ether, and toluene. All conversions were close to 50%, with excellent E values.…”

Síntese de organo-seleno aminas e sua resolução cinética via reação de acetilação enantiosseletiva mediada por lipases

“…Frequentemente faz-se uso de acetato de etila como agente acilante em RCE de aminas36 ; no entanto, em alguns casos, esse éster mostra-se menos adequado em relações a outros doadores de acila127 . A natureza do acilante exerce uma grande influência na conversão e enantiosseletividade do processo de RCE38,115,128 . Uma alta reatividade pode afetar a acilação, de modo que a reação ocorra sem a necessidade de catálise.…”