Diastereoselective synthesis of phosphite triesters

Applications and stereoselective syntheses of P-chirogenic phosphorus compounds

This review reports the best stereoselective or asymmetric syntheses, the most efficient P*-building blocks and functionalisation of P-chirogenic compounds, in the light of chiral phosphorus compound applications.

Synthetic strategies and parameters involved in the synthesis of oligodeoxyribonucleotides according to the phosphoramidite method

The phosphoramidite approach has had a major impact on the synthesis of oligonucleotides. This unit describes parameters that affect the performance of this method for preparing oligodeoxyribonucleotides, as well as a number of compatible strategies. Milestones that led to the discovery of the approach are chronologically reported. Alternate strategies are also described to underscore the versatility by which these synthons can be obtained. Mechanisms of deoxyribonucleoside phosphoramidite activation, factors affecting condensation, and deprotection strategies are discussed.

Indolyl-oxazaphosphorine Precursors for Stereoselective Synthesis of Phosphite Triesters and Dithymidinyl Phosphorothioates

Several novel chiral indolyl-oxazaphosphorines 7 were synthesized, and their potential as precursors to chiral phosphorothioates was evaluated. Reaction of 7 with a thymidine derivative gave phosphite triester 8 with a large degree of stereoselectivity. Sulfurization with Beaucage's reagent provided phosphorothioate triesters 9. The chiral auxiliary 9b containing a cyano group could be easily removed with aqueous ammonia to form dithymidinyl phosphorothioate in more than 97% diastereomeric excess. The chiral indolyl-oxazaphosphorines 7 are a new class of precursors for stereoselective synthesis of phosphorothioates.