220903-72-0Relevant articles and documents
N-substituted 2-(2,6-dinitrophenylamino)propanamides: Novel prodrugs that release a primary amine via nitroreduction and intramolecular cyclization
Sykes, Bridget M.,Atwell, Graham J.,Hogg, Alison,Wilson, William R.,O'Connor, Charmian J.,Denny, William A.
, p. 346 - 355 (2007/10/03)
A series of N-dinitrophenylamino acid amides [(4-CONHZ-2,6- diNO'2Ph)N(R)C(X,Y)CONHPhOMe] were prepared as potential bioreductive prodrugs and reduced radiolytically to study their rates of subsequent intramolecular cyclization. Compounds bearing a free NH group (R = H) underwent rapid cyclization in neutral aqueous buffers (t(1/2) 1 min) following 4-electron reduction, with the generation of a N- hydroxydihydroquinoxalinone and concomitant release of 4-methoxyaniline. Amine release from analogous N-methyl analogues (R = Me) was relatively slow. These results are consistent with intramolecular cyclization of a monohydroxylamine intermediate. The high rates of cyclization/extrusion by these very electron-deficient hydroxylamines suggest that the process is greatly accelerated by the presence of an H-bonding 'conformational lock' between the anilino NH group and the adjacent o-nitro group (Kirk and Cohen, 1972). Changes in the phenylcarboxamide side chain or in C-methylation in the linking chain had little effect on the rate of cyclization. The model compounds had 1-electron reduction potentials in the range appropriate for cellular reduction (-373 mV for a measured example) and appeared suitable for development as prodrugs that release amine-based effectors following enzymic or radiolytic reduction. Prodrug examples containing 4-aminoaniline mustard and 5-amino-1-(chloromethyl)benz[e]indoline alkylating units were evaluated but were not activated efficiently by cellular nitroreductases. However, cell killing by the radiation-induced reduction of the latter prodrug was demonstrated.
