- Oxidation of acetylpolyamines by maize polyamine oxidase
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The oxidation of acetylpolyamines by celt wall polyamine oxidase from maize shoots was investigated. The purified enzyme catalysed the oxidation of N1-acetylspermine, N1-acetylspermidine, and N8-acetylspermidine at the same optimal pH (6.5), but with lower relative velocities and higher K(m) than those found for spermine and spermidine oxidation. The enzyme cleaved N1-acetylspermine and N8-acetylspermidine, at the same positions as in spermine and spermidine oxidation, with the production of H2O2, 1,3- diaminopropane and the corresponding aminoaldehydes. Polyamine oxidase was quickly inactivated by catalysis, and the aminoaldehyde derived from N1- acetylspermine behaved as a competitive inhibitor of the enzyme (K(m) = 20 μM). These findings suggest that cell wait polyamine oxidase from maize shoots does not effect the interconversion pathway of acetylpolyamines found in vertebrates.
- Federico, Rodolfo,Ercolini, Luca,Laurenzi, Maria,Angelini, Riccardo
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p. 339 - 341
(2007/10/03)
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- Amide-directed hydrocarbonylation of N-alkenylamides and α-alkenyllactams
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The amide-directed Rh-catalyzed hydroformylation and Pd-catalyzed hydroesterification of N-allylamides give the iso-aldehyde and ester, respectively, with good regioselectivity.The Rh- and Co2Rh2(CO)12-catalyzed reactions of N-methallylamide give an 1-acyl-2-formylpyrrolidine through a novel double carbonylation and an 1-acylpyrrolidine through reductive annulation, respectively, with excellent selectivity.A cyclic hemiamidal, N-benzoyl-2-hydroxy-4-methylpyrrolidine, the key intermediate for the double carbonylation and the reductive annulation, is obtained selectively in a Rh4(CO)12-catalyzed reaction of N-methallylamide.The hydrocarbonylations of this cyclic hemiamidal catalyzed by RhCl(PPh3)3, Co2Rh2(CO)12, and Co2(CO)8 give the corresponding double carbonylation product (2-formylpyrrolidine), reductive annulation product (pyrrolidine), and amidocarbonylation product (proline), respectively, in excellent yield and selectivity.The mechanisms of the novel double carbonylation and the reductive annulation is studied on the basis of deuterium-labeling experiments, and it is found that these reactions proceed via enamide intermediate followed by extremely regioseletive metal hydride addition to the enamide.The Rh-catalyzed hydrocarbonylations of the α-methallyl-γ- and δ-lactams in triethyl orthoformate followed by treatment with TFA give the corresponding 1-azabicycloalkenones via bicyclic hemiamidals through annulation in excellent overall yields.The Co2Rh2(CO)12-catalyzed reactions of these α-methallyl lactams give the corresponding 1-azabicycloalkanones as the sole isolable products in high yields.The RhCl(PPh3)3-catalyzed hydrocarbonylation of 6-allylpiperidin-2-one givesa mixture of 1-azabicyclo and 1-azabicyclo products.However, the addition of phosphines to the Rh catalyst remarkably improves the normal selectivity (n/iso = 9) to give 1-azabicyclodec-2-en-10-one as the predominant product.
- Ojima, Iwao,Zhang, Zhaoda
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p. 253 - 276
(2007/10/02)
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- Novel Amide-Directed Hydrocarbonylation and Double Carbonylation of N-Allylamides
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The rhodium-catalyzed hydroformylation and palladium-catalyzed hydroesteryfication of N-allylamides give isoaldehyde (1) and isoester (5), respectively, with good regioselectivity through chelation control while the rhodium- and Co2Rh2(CO)12-catalyzed reactions of an N-methallylamide give a novel double carbonylation product (10) and a pyrrolidine (11), respectively, with exellent selectivity.
- Ojima, Iwao,Zhang, Zhaoda
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p. 4422 - 4425
(2007/10/02)
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