The lithium salts of the conjugated bases of 4-methoxy- and 4-acetylamino-2(1H)-pyrimidinones 1-3 undergo highly chemoselective N1-methylation or ethylation when treated with methyl- or ethylsulphate (hard electrophiles) in dry dioxane, while the use of DMF as solvent results in competitive O2-alkylation. Potassium salts of the same bases in DMF undergo prevalent O2-attack. Under the same conditions, a similar but less chemoselective behaviour is observed in alkylation of thymine and uracil, where some N3-attack occurs. This can be rationalized in terms of the HSAB principle. -
Augusto, G., Tofani, D., MARIA ANTONIETTA, L., Gasperi, T., Roberta, B. (2006). HSAB-Driven Chemoselective N1-Alkylation of Pyrimidine Bases and Their 4-Methoxy- or 4-Acetylamino-Derivatives. TETRAHEDRON, 62, 6848-6854 [10.1016/j.tet.2006.04.098].
HSAB-Driven Chemoselective N1-Alkylation of Pyrimidine Bases and Their 4-Methoxy- or 4-Acetylamino-Derivatives
TOFANI, DANIELA;GASPERI, TECLA;
2006-01-01
Abstract
The lithium salts of the conjugated bases of 4-methoxy- and 4-acetylamino-2(1H)-pyrimidinones 1-3 undergo highly chemoselective N1-methylation or ethylation when treated with methyl- or ethylsulphate (hard electrophiles) in dry dioxane, while the use of DMF as solvent results in competitive O2-alkylation. Potassium salts of the same bases in DMF undergo prevalent O2-attack. Under the same conditions, a similar but less chemoselective behaviour is observed in alkylation of thymine and uracil, where some N3-attack occurs. This can be rationalized in terms of the HSAB principle. -I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
