Modulating the Stability of 2-Pyridinyl Thermolabile Hydroxyl Protecting Groups via the “Chemical Switch” Approach
作者:Agnieszka Witkowska、Dominika Krygier、Jolanta Brzezinska、Marcin K. Chmielewski
DOI:10.1021/acs.joc.5b02033
日期:2015.12.18
A novel and effective method is presented for modulating the stability of 2-Pyridinyl Thermolabile Protecting Groups (2-Py TPGs) in the "chemical switch" approach. The main advantage of the discussed approach is the possibility of changing the nudeophilic character of pyridine nitrogen using different switchable factors, which results in an increase or decrease in the thermal deprotection rate. One of the factors is transformation of a nitro into an amine group via reduction with a low-valent titanium in mild conditions. The usefulness of our approach is corroborated using 3'-O-acetyl nucleosides as model compounds. Their stability in various solvents and temperatures before and after reduction is also examined. Pyridine N-oxide and pH are other factors responsible for the nudeophilicity and stability of 2-Pyridinyl Thermolabile Protecting Groups in thermal deprotection. Protonation of 4-amino 2-Pyridinyl Thermolabile Protecting Groups is demonstrated by H-1-N-15 HMBC and HSQC NMR analysis.
Microwave-Dependent Thermo-Release Approach for Oligonucleotides 5′-Phosphorylation
作者:Dominika Krygier、Mikołaj Przybyła、Marcin K. Chmielewski
DOI:10.1021/acs.orglett.3c03924
日期:2024.2.16
A method for phosphorylating oligonucleotides using a thermosensitive “trigger” is hereby presented. The recovery of the phosphate specifically takes place under neutral conditions when subjected to an elevated temperature. Two identical thermolabile protecting groups are differentially removed with the initial release occurring swiftly and the second at a more gradual pace. The delayed deprotection