38642-30-7Relevant academic research and scientific papers
Synthesis of pyrimidine 2′-deoxy ribonucleosides branched at the 2′-position via radical atom-transfer cyclization reaction with a vinylsilyl group as a radical-acceptor tether
Sukeda,Shuto,Sugimoto,Ichikawa,Matsuda
, p. 8988 - 8996 (2007/10/03)
Recently, we developed a regio- and stereoselective method for introducing a vinyl group at the position β to a hydroxyl group in halohydrins or α-phenylselenoalkanols via a radical atom-transfer cyclization reaction with a vinylsilyl group as a temporary connecting radical-acceptor tether. The synthesis of 2′-deoxy-2′-C-vinyl- and 2′-deoxy-2′-C-hydroxymethyluridines (7 and 8, respectively) and the corresponding 2′-deoxycytidine congeners (10 and 11, respectively), which were designed as potential antitumor and/or antiviral agents, was achieved using this radical atom-transfer cyclization as the key step. When the 2′-deoxy-2′-iodo-5′-O-monomethoxytrityl (MMTr) uridine derivative 19a, bearing a vinylsilyl group at the 3′-hydroxyl group, was heated with (Me3Sn)2 and AIBN in benzene, the corresponding radical atom-transfer product was generated, which in turn was successively treated with tetrabutylammonium fluoride and TBSCI/imidazole to give the desired 2′-deoxy-5′-O-MMTr-3′-O-TBS-2′-C-vinyluridine (25). Compound 25 was successfully converted into the target 2′-deoxy-2′-branched pyrimidine ribonucleosides 7, 8, 10, and 11.
Nucleosides. Part LIX. The 2-(4-nitrophenyl)ethylsulfonyl (Npes) group: A new type of protection in nucleoside chemistry
Pfister,Schirmeister,Mohr,Farkas,Stengele,Reiner,Dunkel,Gokhale,Charubala,Pfleiderer
, p. 1705 - 1737 (2007/10/02)
The 2-(4-nitrophenyl)ethylsulfonyl (npes) group is developed as a new sugar OH-blocking group in the ribonucleoside series. Its cleavage can be performed in a β-eliminating process under aprotic conditions using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the most effective base. Since sulfonates do not show acyl migration, partial protection of 1,2-cis-diol moieties is possible leading to new types of oligonucleotide building blocks. A series of Markiewicz-protected ribonucleosides 1-10 is converted into their 2'-O-[2-(4-nitrophenyl)ethylsulfonyl] derivatives 29-38 in which the 5'-O-Si bond can be cleaved by acid hydrolysis forming 39-45. Subsequent monomethoxytritylation leads to 46-50, and desilylation affords the 5'-O-(monomethoxytrityl)-2'-O-[2-(4-nitrophenyl)ethylsulfonyl]ribonucl eosides 51-55. Acid treatment to remove trityl groups do also not harm the npes group(→ 56-58). Unambiguous syntheses of fully blocked 2'-O-[2-(4-nitrophenyl)ethylsulfonyl]ribonucleosides 96-102 are achieved from the corresponding 3'-O-(tert-butyl)dimethylsilyl derivatives. Furthermore, various base-protected 5'-O-(monomethoxytrityl)- and 5'-O-(dimethoxytrityl)ribonucleosides, i.e. 59-77, are treated directly with 2-(4-nitrophenyl)ethylsulfonyl chloride forming in all cases a mixture of the 2',3'-di-O- and the two possible 2'- and 3'-O-monosulfonates 107-148 which can be separated into the pure components by chromatographic methods. The npes group is more labile towards DBU cleavage than the corresponding base-protecting 2-(4-nitrophenyl)ethyl (npe) and 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) groups allowing selective deblocking which is of great synthetic potential.
The preparation of protected arabinonucleosides
Ogilvie, Kelvin K.,McGee, Danny P. C.,Boisvert, Suzanne M.,Hakimelahi, Gholam H.,Proba, Zbigniew A.
, p. 1204 - 1212 (2007/10/02)
A general procedure is described for the preparation of protected arabinonucleosides.Protection at the 5'-position involves triphenylmethyl groups (DMT and MMT) while the tert-butyldimethylsilyl (TBDMS) group is used to protect the 2'- or 3'-positions.The
