Collect. Czech. Chem. Commun. 1986, 51, 1972-1985

Formation of the Meisenheimer spiro adduct of N-(2,4,6-trinitrophenyl)alanine methylamide and its rearrangement to 2-amino-N-methyl-N-(2,4,6-trinitrophenyl)propanamide

Vladimír Macháčeka, Makky M. M. Hassaniena, Vojeslav Štěrbaa and Antonín Lyčkab

a Department of Organic Chemistry, Institute of Chemical Technology, 532 10 Pardubice
b Research Institute of Organic Syntheses, 532 18 Pardubice-Rybitví


N-(2,4,6-trinitrophenyl)alanine methylamide (I) undergoes base-catalyzed cyclization in methanol to give the spiro adduct II. In aniline-anilinium chloride buffers, the spiro adduct is protonated at the oxygen atom of 2-nitro group to give the neutral compound III. In 4-bromoaniline buffers or by action of methanolic hydrogen chloride, the compound III is opened to E and Z isomers of 2-amino-N-methyl-N-(2,4,6-trinitrophenyl)propanamide hydrochloride (IV). The rate-limiting step of cyclization of compound Z-IV to compound III consists in the isomerization Z-IVE-IV. At higher pH values (acetate buffers), the rate-limiting step is gradually changed to the isomerization of 2-amino-N-methyl-N-(2,4,6-trinitrophenyl)propanamide (Z-VE-V).