The use of dialkyl acetals in the N-alkylation of 8-oxoadenosine and guanosine. Mechanistic studies and rate determination
作者:Tewoderos Ayele、Stephanie J. Chang、Marino J.E. Resendiz
DOI:10.1016/j.tetlet.2015.06.002
日期:2015.7
The use of seven N,N-dimethylformamide dialkyl acetals (methyl-, ethyl-, benzyl-, n-propyl-, n-butyl-, t-butyl, and neopentyl-) was explored for the exocyclic amine protection and subsequent N-alkylation of 8-oxoadenosine and guanosine. Reactions occurred in good to modest yields (50-95%) upon addition of heat (60 degrees C) using DMF as solvent. We determined relative rates of reaction and kinetic experiments resulted in the following order: Me >> Bn approximate to t-Bu >> Et approximate to n-Pr approximate to n-Bu > Me (Np, neopentyl). We found that groups that stabilize a pseudo-carbocation intermediate facilitate the completion of the reaction and lead to different reaction pathways, including elimination of isobutylene and ethylene in some cases. (C) 2015 Elsevier Ltd. All rights reserved.