Microwave-Dependent Thermo-Release Approach for Oligonucleotides 5'-Phosphorylation.

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.

2-Pyridinyl Thermolabile Groups as General Protectants for Hydroxyl, Phosphate, and Carboxyl Functions.

Application of 2-pyridinyl thermolabile protecting groups (2-PyTPGs) for protection of hydroxyl, phosphate, and carboxyl functions is presented in this unit. Their characteristic feature is a unique removal process following the intramolecular cyclization mechanism and induced only by temperature rise. Deprotection rate of 2-PyTPGs is dependent on certain parameters, such as solvent (aqueous or non-aqueous medium), pH values, and electron distribution in a pyridine ring.

Modulating the Stability of 2-Pyridinyl Thermolabile Hydroxyl Protecting Groups via the "Chemical Switch" Approach.

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 nucleophilic 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.