Tautomeric equilibria in the reaction products of asymmetric 1,3-diamines with β-dicarbonyl compounds |
| |
Authors: | Olga A Maloshitskaya Valery V Alekseyev Kirill N Zelenin Kalevi Pihlaja |
| |
Institution: | a Department of Chemistry, Structural Chemistry Group, University of Turku, FI-20014 Turku, Finland b Russian Military Medical Academy, 194044 St. Petersburg, Russian Federation |
| |
Abstract: | The reaction products of 1,3-butanediamine and 2-methyl-2,4-pentanediamine with β-keto aldehydes were shown by 1H and 13C NMR spectroscopy to exist as tautomeric mixtures in solutions, comprising one cyclic and two open-chain forms due to the non-equivalence of the amino groups. The chain products exist as Z- and E-isomers. After equilibration, the products from 1,3-butanediamine contain relatively less of the cyclic form than those from 2-methyl-2,4-pentanediamine. The products of 2-methyl-2,4-pentanediamine with p-substituted aroylacetaldehydes, exhibit a linear correlation between log K of the ring-chain equilibria and Hammett's σ values of the aromatic ring substituents. α-Substitution of β-keto aldehydes notably increased the relative amounts of the chain E-isomers in their condensation products and also resulted in the formation of two diastereomers for each of the cyclic products. No ring-chain equilibria were observed in the products of 1,3-butanediamine and 2-methyl-2,4-pentanediamine with β-diketones, β-keto esters, or β-keto amides. |
| |
Keywords: | Ring-chain tautomerism Hexahydropyrimidines β-Dicarbonyl compounds 1 3-Diamines |
本文献已被 ScienceDirect 等数据库收录! |
|