Efficient synthesis of extended guanine analogues designed for recognition of an A·T inverted base pair in triple helix based-strategy

FeCl3-promoted and ultrasound-assisted synthesis of resveratrol O-derived glycoside analogs

Phenol derived O-glycosides were synthesized using a direct and convenient O-glycosidation, starting from acetylated sugars in the presence of FeCl3, an inexpensive, mild and benign Lewis acid catalyst. The reactions were carried out under both conventional and ultrasonic irradiation conditions. In general, improvement in rates and yields were observed when reactions were carried out under sonication compared with conventional conditions leading to the corresponding β-O-glycosides as the major anomer. Post-synthetic transformations of iodophenol intermediates led to new resveratrol O-glycoside analogs in good overall yields.

A practical post-modification synthesis of oligodeoxynucleotides containing 4,7-diaminoimidazo[5',4':4,5]pyrido[2,3-d]pyrimidine nucleoside

We describe herein the practical post-modification synthesis of oligodeoxynucleotides (ODNs) containing 4,7-diaminoimidazo[5',4':4,5]pyrido[2,3-d]pyrimidine nucleoside (ImN(N)). Since the ImN(N) nucleoside unit possessing tribenzoyl groups on its exocyclic amino groups as the protecting group was quite unstable under acidic conditions, cleavage of its glycosidic linkage in ODN has been suggested throughout the conditions of solid-phase synthesis. As an alternative approach, we investigated a post-modification synthesis of the desired ODNs containing the ImN(N) unit. Starting with protected 4-amino-7-chloro-1-(2-deoxy-β-D-ribofuranosyl)imidazo[5',4':4,5]pyrido[2,3-d]pyrimidine derivative 1, conversion into the corresponding phosphoramidite unit was examined. The p-bromobenzoyl group (p-BrBz) was the best protecting group of 4-amino group of 1 to give the phosphoramidite unit 9 for the post-modification synthesis. After carrying out the ODN synthesis linked to the controlled pore glass (CPG) support, the support was treated with ammonium hydroxide at 55 °C to remove the protecting groups, detach the ODN form the CPG support, and convert the 7-chloro group into a desired amino group. As a result, the desired ODNs containing ImN(N) were obtained in good yield.

Synthesis and triplex-forming ability of oligonucleotides bearing 1-substituted 1H-1,2,3-triazole nucleobases

Using the copper(I)-catalyzed alkyne-azide 1,3-dipolar cycloaddition, a post-elongation modification of 1-ethynyl substituted nucleobases has been employed to construct 18 variations of oligonucleotides from a common oligonucleotide precursor. The triplex-forming ability of each oligonucleotide with dsDNA was evaluated by the UV melting experiment. It was found that triazole nucleobases generally tend to exhibit binding affinities in the following order: CG>TA>AT, GC base pairs. Among the triazole nucleobases examined, a 1-(4-ureidophenyl)triazole provided the best result with regard to affinity and selectivity for the CG base pair.

Targeting DNA base pair mismatch with artificial nucleobases. Advances and perspectives in triple helix strategy

This review, divided into three sections, describes the contribution of the chemists' community to the development and application of triple helix strategy by using artificial nucleic acids, particularly for the recognition of DNA sequences incorporating base pair inversions. Firstly, the development of nucleobases that recognise CG inversion is surveyed followed secondly by specific recognition of TA inverted base pair. Finally, we point out in the last section recent perspectives and applications, driven from knowledge in nucleic acids interactions, in the growing field of nanotechnology and supramolecular chemistry at the border area of physics, chemistry and molecular biology.