161001-84-9Relevant academic research and scientific papers
Kinetics and mechanisms of the gas-phase elimination of arylethyl N,N-dimethylcarbamates and ω-phenylalkyl N,N-dimethylcarbamates
Chuchani, Gabriel,Dominguez, Rosa M.,Rotinov, Alexandra,Herize, Armando
, p. 40 - 46 (2007/10/03)
The gas-phase elimination kinetics of several arylethyl N,N-dimethylcarbamates and ω-phenylalkyl N,N-dimethylcarbamates were determined in the temperature range 299.6-399.9 °C and pressure range 18-95 Torr. The reactions in a static system, seasoned with allyl bromide, and in the presence of a free radical suppressor are homogeneous and unimolecular and follow a first-order rate law. The rate coefficients are given by the Arrhenius equations: for 4-phenethyl N,N-dimethylcarbamate, log [k1 (s-1)] = (11.32 ± 0.22) - (166.9 ± 2.5) kJ mol-1 (2.303RT)-1; for methylphenethyl N,N-dimethylcarbamate, log[k1 (s-1)] = (12.07 ± 0.36) - (178.6 ± 4.3) kJ mol-1 (2.303RT)-1; for 4-methoxyphenethyl N,N-dimethylcarbamate, log[k1 (s-1)] = (11.03 ± 0.60) - (167.3 ± 7.1) kJ mol-1 (2.303RT)-1; for 4-nitrophenethyl N,N-dimethylcarbamate, log[k1 (s-1)] = (11.31 ± 0.54) - (163.7 ± 6.1) kJ mol-1 (2.303 RT)-1; for 3-(4-methoxyphenyl) propyl N,N-dimethylcarbamate, log [k1 (s-1)] = (13.52 ± 0.54) - (208.4 ± 6.8) kJ mol-1 (2.303 RT)-1; for 4-phenyl-1-butyl N,N-dimethylcarbamate, log [k1 (s-1)] = (12.00 ± 0.34) - (185.2 ± 4.2) kJ mol-1 (2.303 RT)-1; and for 5-phenyl-1-pentyl N,N-dimethyl carbamate, log [k1 (s-1)] = (11.79 ± 0.31) - (182.2 ± 3.9) kJ mol-1 (2.303RT)-1. The results imply the absence of anchimeric assistance of the phenyl group, while the acidity of the benzylic β-hydrogen appears to be responsible for a small but significant rate augmentation in these eliminations. Copyright
Nucleosides. Part LVI. Aminolysis of carbamates of adenosine and cytidine
Sigmund,Pfleiderer
, p. 1267 - 1280 (2007/10/02)
The 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) group, introduced 1984 as protecting group for exocyclic amino functions of nucleic-acid bases, reacts with amines under mild conditions to urea derivatives. Treatment of 2',5'-di-O-acetyl-N6-[2-(4-nitrophenyl)ethoxycarbonyl]cordycepin (3) with NH3/MeOH overnight at room temperature affords cordycepin (4) and N6-carbamoylcordycepin (5). Preliminary investigations towards the elucidation of the reaction mechanism indicate that the aminolysis proceeds via an addition-elimination or an isocyanate mechanism, depending on the reaction conditions. The phenoxycarbonyl (phoc) group at N6 or N4 was chosen to study the mild conversion of carbamates with aromatic amines into ureas of adenosine and cytidine, respectively.
