Nucleosides protected

In a quest to develop the perfect nucleoside protection scheme, the Cpeoc group was devised for protection of the 5 -OH. It is introduced through the chloro-formate in 58-83% yield. Cleavage is achieved with 0.1 M DBU with half-lives of 7-14 sec, depending on the nucleoside. ... 

The most commonly used thiation reagents (see [166] for a discussion about thiation reagents) and particularly P4Sl0 and its surrogates are not suitable for acid-labile compounds. Some mild methods have been devised, for instance the conversion of nucleosides to thionucleosides [167], an example of which is given here. The nucleoside (protected on the sugar... 

Nucleosides, protection or primary OH Di-p-anisylphenylmethyl chloride. 2,2-Dimethoxy-propane. 

A new method for the preparation of 5 -amino-5 -deox)mucleotides has been described, based on the reaction between phosphorus triesters and phenyl azide. Treatment of protected 5 -azido-5 -deoxynucleosides with trimethyl or triphenyl phosphite leads, after removal of the nucleoside protecting groups and one of the esterifying groups from the phosphoryl residue, to the phosphoramidates (9). Snake venom phosphodiesterase hydrolyses (9) to 5 -aminonucleosides. 

Treatment of bromomethyl acetate with the sodium salt of a dialkyl phosphite, followed by deacetylation with methoxide affords the corresponding dialkyl hydroxymethanephosphonate. If this is tosylated with tosyl chloride, and the product treated with nucleosides [protected at the 3 -(and 2 -, if present) hydroxy groups] and sodium hydride in DMF, the monoalkyl ester of a 5 -0-phosphonyl-methyl nucleoside (60) is obtained after deblocking the sugar, and subsequent dealkylation with TMS-iodide affords (61). Like alkyl esters of 5 -mononucleotides, (60) is resistant to acid and alkaline hydrolysis, while (61) is stable in acidic and alkaline media, and is also resistant to hydrolysis by alkaline phosphomono-esterase and snake venom 5 -nucleotidase. Treatment of (61) with DCC and morpholine, and subsequently with orthophosphate or pyrophosphate, affords (62) and (63), respectively. Alkaline phosphomonoesterase from E. co/i hydrolyses the pyrophosphate links in (62) and (63) to give (61) and orthophosphate. The UTP and CTP analogues (63 B = U or C) are inhibitors of uridine kinase from... 

Reproduced from Girl N, Bowen C, Vyle JS, James SL. Fast, quantitative nucleoside protection under solvent-free conditions. Green Chem 2008 10 627-8, with permission from the Royal Society of Chemistry. 

A series of 3 -phosphoreonidite derivatives of 2 -deoxyribo-nucleosides protected at 0-5 have been synthesized in connection with oligonucleotide synthesis,and the non-aqueous oxidation of nucleoside phosphites to phosphates has been studied, with bis-... 

There have been a number of reports on phosphonate analogues of nucleoside monophosphates, including a further paper on 2, 3 -dideoxy-3 -phosphonomethyl analogues (see Vol. 18, p.203) which reports the guanosine compound (176) for the first time.23i Phosphonoformate esters of anti-HIV nucleosides, such as (177), have been prepared,232 as has the 5 -0-phosphonomethyl compound (178), by alkylation of the unsaturated nucleoside, protection of the uracil NH being necessary.23 3 xhe isosteric phosphonates of type (179) have also been made, as outlined in Scheme 23, with the unsaturated thymidine member being a potent antiretroviral agent.234,235 x e phosphonomethyl derivative (180) of 3 -deoxy-3 -... 

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