Phosphoramidite method

Oligonucleotide Synthesis (phosphoramidite method - Lessinger) Review Tetrahedron 1992, 48,2223... 

Chirahty at the phosphoms is an unavoidable problem in all phosphorothioate syntheses. The phosphoramidite method produces a mixture of both the and the diastereomers having a small excess of the isomer (53). Although some progress has been made in the chiral synthesis of dinucleoside phosphorothioates, low yields have limited the utility of these approaches. The chiral center may be eliminated by replacing the other, nonbridging oxygen with sulfur. Avoidance of the chirahty problem is one reason for the interest in phosphorodithioates. 

Phosphate triesters (18) are iatermediates ia both the phosphotriester and phosphoramidite methods, and under appropriate conditions for deprotection of the bases and cleavage of the support, can be obtained directiy by usiag these approaches. The ethyl and isopropyl esters have been obtained directiy by usiag the phosphoramidite method because these are stable duting the normal deprotection procedure (62). By changing the oxidizing agent to Sg, both amidate and triester thiolates can be obtained. 

The a-anomeric form of a 2 -deoxyribose, which has the base inverted with respect to the natural P-anomeric form, can be synthesized by using the phosphoramidite method sugar modification renders the derivatives nuclease-resistant. These analogues form parallel duplexes with complementary RNA... 

The cyclohexyl phosphate, used in the protection of phosphorylated serine derivatives, is introduced by the phosphoramidite method and cleaved with TFMSA/MTB/m-cresol/l,2-ethanedithiol/TFA, 4 h, 0° to rt. " ... 

Fig. 19 Basic steps in a cycle of nucleotide addition by the phosphoramidite method in-situ synthesis using ink-jetting. DMTr = dimethoxytrityl group...

Modified oligonucleotides, synthesis by phosphoramidite method and application 93T6123. 

Synthesis of specific ribonucleotides by the phosphoramidite method 93T10441. 

SoUD PHASE SYNTHESIS OF A POLYNUCLEOTIDE BY THE PHOSPHORAMIDITE METHOD. 

Show a synthesis of this trinucleotide using the phosphoramidite method ... 

Oligonucleotide primers are synthesized with an Applied Biosystems 380A synthesizer by the phosphoramidite method T4 polynucleotide kinase (10 U//il) is obtained from Amersham (Amer-sham, UK)... 

The Synthesis of Specific Ribonucleotides and Unrelated Phosphorylated Biomolecules by the Phosphoramidite Method, Beaucage, S. L. Iyer, R. P Tetrahedron 1993, 49, 10441-10488. 

The procedure, based on the phosphoramidite method, is illustrated in Scheme 7.11. Nn-Fmoc-L-tyrosine was temporarily protected as its ferf-butyldimethylsilyl ester (see section 6.6). Phosphitylation with dimethyl tyN-diethylphosphorami-dite followed by in situ oxidation with /erf-butyl hydroperoxide gave the phos-phodiester 11 3 The labile silyl ester hydrolysed during the sodium metabisulfite workup used to destroy excess /erf-butyl hydroperoxide to give 11.4 in 57% overall yield, By the same procedure, the dkerf-butyl phosphate 11.5, dibenzyl phosphate 11.6 and diallyl phosphate (not shown) were prepared. 

AUyl esters are typically prepared by the revenant phosphoramidite method.17 45... 

Cyanoethyl phosphates are usually prepared by the phosphoramidite method using 2-cyanoethyl tyN-diisopropylchlorophosphoramidite,66 67 2-cyanoethyl N.tyN pN -tetraisopropylphosphordiamidite5 or bis(2-cyanoethyl) MN-diisopro-pylchlorophosphoramidite.71... 

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