# Bond Formation at C8 in the Nucleoside and Nucleotide Purine Scaffold: An Informative Selection

## TL;DR

This paper explores chemical methods to modify the C8 position of purine nucleosides and nucleotides, focusing on bond formation techniques.

## Contribution

The paper introduces new methods for selective and functional-tolerant C8 bond formation in purine scaffolds.

## Key findings

- Metal-promoted cross-coupling reactions enable efficient carbylation at the C8 position.
- Direct oxidative metalation using sterically hindered metal amides provides high selectivity and simplicity.
- Metal-assisted reactions are effective for both nucleobases and their glycosides.

## Abstract

This paper presents methods for the introduction and exchange of substituents in a nucleobase and its nucleosides and nucleotides with emphasis on the C8-position in the purine skeleton. The nucleobase is open for electrophilic and nucleophilic chemistry. The nucleophilic chemistry consists mainly of displacement reactions when the C8-substituent is a good leaving group such as a halogen atom. The heteroatom in amines, sulfides, or oxides is a good nucleophile. Halides are good reaction partners. Metal-promoted cross-coupling reactions are important for carbylations. Direct oxidative metalation reactions using sterically hindered metal amides offer chemo- and regio-selectivity besides functional tolerance and simplicity. The carbon site is highly nucleophilic after metalation and adds electrophiles resulting in chemical bond formation. Conditions for metal-assisted reactions are described for nucleobases and their glycosides.