The lithium salts of the conjugated bases of 4-methoxy- and 4-acetylamino-2(1H)-pyrimidinones 1-3 undergo highly chemoselective N-1-methylation or ethylation when treated with methyl- or ethylsulfate (hard electrophiles) in dry dioxane, while the use of DMF as solvent results in competitive O-2-alkylation. Potassium salts of the same bases in DMF undergo prevalent O-2-attack. Under the same conditions, a similar but less chemoselective behaviour is observed in alkylation of thymine and uracil, where some N-3 -attack occurs. This can be rationalised in terms of the HSAB principle
Gambacorta, A., Tofani, D., LORETO M., A., Gasperi, T., Bernini, R. (2006). HSAB-driven chemoselective N1-alkylation of pyrimidine bases and their 4-methoxy- or 4-acetylamino-derivatives. TETRAHEDRON, 62, 6848-6854.
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 N-1-methylation or ethylation when treated with methyl- or ethylsulfate (hard electrophiles) in dry dioxane, while the use of DMF as solvent results in competitive O-2-alkylation. Potassium salts of the same bases in DMF undergo prevalent O-2-attack. Under the same conditions, a similar but less chemoselective behaviour is observed in alkylation of thymine and uracil, where some N-3 -attack occurs. This can be rationalised in terms of the HSAB principleI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
