Pirolidinski derivati u organokatalitičkim transformacijama

Abstract

Hiralni, polisupstituisani derivati pirolidina, dobijeni cikloadicionim reakcijamaazometinskih ilida, proučavani su kao organokatalizatori u Michael-ovoj reakciji aldehida/ketonai vinil-sulfona. Pod optimalnim reakcionim uslovima, u kojima se koristilo 10 mol % katalizatorau vlažnom metilen-hloridu prinosi reakcija su generalno bili dobri dok je enantioselektivnostvarirala dostižući 52 %.Razvijen je efikasan biokatalizator za asimetričnu Michael-ovu adiciju acetaldehida na β-nitrostiren na bazi celih ćelija koja eksprimira 4-oksalokrotonat tautomerazu (4-OT). Utvrđen jeoptimalan odnos supstrata i biokatalizatora. Kada je kao supstrat korišćen β-nitrostiren dobijenaje odlična enantioselektivnost (e.e. >99%) uz prinos reakcije do 60%. Biokatalizator je manjeefikasan sa p-hlor-, o-hlor- i p-fluor-β-nitrostirenom gde su dobijeni prinosi od 38%, 51%, 31% ie.e. 84%, 88%, 94%...

Chiral, polysubstituted pirrolydines derivatives, obtained via cycloaddition reactions ofazomethine ylides, were studied as organocatalysts in the Michael reaction of aldehydes/ketonesand vinylsulphones. Under optimised reaction conditions employing 10 mol % of the catalyst inwet CH2Cl2, the yields of the products were generally good while the enantioselectivity varied,reaching up to 52 %.A novel whole cell system based on recombinantly expressed 4-oxalocrotonatetautomerase (4-OT) was developed and shown to be an effective biocatalyst for the asymmetricMichael addition of acetaldehyde to β-nitrostyrenes. Optimal ratio of substrates and biocatalystwas determined. Excellent enantioselectivity (>99% ee) and product yields of up to 60% wereobtained with β-nitrostyrene substrate. The biocatalyst exhibited lower reaction rates with pchloro-,o-chloro- and p-fluoro-β-nitrostyrenes with product yields of 38%, 51%, 31% and eevalues of 84%, 88% and 94% respectively...