88121-72-6Relevant academic research and scientific papers
Nucleosides. Part LI. The 2-(4-Nitrophenyl)ethoxycarbonyl (npeoc) and 2-(2,4-Dinitrophenyl)ethoxycarbonyl (dnpeoc) Groups for Protection of Hydroxy Functions in Ribonucleosides and 2'-Deoxyribonucleosides
Schirmeister, Helga,Himmelsbach, Frank,Pfleiderer, Wolfgang
, p. 385 - 401 (2007/10/02)
The common 2'-deoxypyrimidine and -purine nucleosides, thymidine (4), O4-thymidine (17), 2'-deoxy-N4-cytidine (26), 2'-deoxy-N6-adenosine (39), and 2'-deoxy-N2--O6-guanosine (52) were further protected by the 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) and the 2-(2,4-dinitrophenyl)ethoxycarbonyl (dnpeoc) group at the OH functions of the sugar moiety to form new partially and fully blocked intermediates for nucleoside and nucleotide syntheses.The corresponding 5'-O-monomethoxytrityl derivatives 5, 18, 30, 40, and 56 were also used as starting material to synthesize some other intermediates which were not obtained by direct acylations.In the ribonucleoside series, the 5'-O-monomethoxytrityl derivatives 14, 36, 49, and 63 reacted with 2-(4-nitrophenyl)ethyl chloroformate (1) to the corresponding 2',3'-bis-carbonates 15, 37, 50, and 64 which were either detritylated to 16, 38, 51, and 65, respectively, or converted by 1,8-diazabicycloundec-7-ene (DBU) treatment to the 2',3'-cyclic carbonates 66-69.The newly synthesized compounds were characterized by elemental analyses and UV and 1H-NMR spectra.
THE p-NITROPHENYLETHYL (NPE) GROUP. A VERSATILE NEW BLOCKING GROUP FOR PHOSPHATE AND AGLYCONE PROTECTION IN NUCLEOSIDES AND NUCLEOTIDES
Himmelsbach, Frank,Schulz, Bernd S.,Trichtinger, Thomas,Charubala, Ramamurthy,Pfleiderer, Wolfgang
, p. 59 - 72 (2007/10/02)
The syntheses of new monomeric building blocks for oligonucleotide synthesis via the phosphotriester approach containing the p-nitrophenylethyl group for phosphate and aglycone protection are described.Blocking of the amide function in guanosines at O6 can be achieved by the Mitsunobu reaction forming the corresponding O6-p-nitrophenylethyl derivatives (4,5,10).Sugar-protected thymidine (16) and uridine (17) have been alkylated at O4 in an SN1-type reaction by p-nitrophenylethyl iodide-silver carbonate in benzene to form the O4-p-nitrophenylethyl derivatives (18,19).Protection of the amino group in 2'-deoxycytidine (25) and cytidine (26) can be performed directly by 1-(p-nitrophenylethoxycarbonyl)-benzotriazole in DMF to obtain the corresponding carbamates (27,28) as a new type of N4-acylated cytidine derivative. p-Nitrophenylethoxycarbonylation of the amino group in 2'-deoxyadenosine (33) and adenosine (34) requires previous sugar protection by acyl or silyl groups and can then be achieved by p-nitrophenylethyl chloroformate or better by 1-methyl-3-p-nitrophenylethoxycarbonylimidazolium chloride to form N6-p-nitrophenylethoxycarbonyladenosines (38,39,40,42).The various p-nitrophenylethyl blocking groups are stable under mild hydrolytic conditions (e.g. ammonia and triethylamine) but can be cleaved selectively by DBU or DBN in aprotic solvents. 5'-O-Monomethoxytritylation (12,29,43) as well as phosphorylations at the 3'-OH group can be effected to give the corresponding 3'-(2,5-dichlorophenyl,p-nitrophenylethyl)-phosphotriesters (13,22,30,44) also in high yields.Oximate cleavage of the latter compounds to the phosphodiesters (14,24,32,46) and detritylation to the 5'-unblocked phosphotriesters (15,23,31,45) do not affect the aglycone protecting groups, thereby demonstrating their general versatility.The newly synthesized compounds have been characterized on the basis of their elementary analyses (C,N,H), and UV- and 1H-HMR-spectra.
THE USE OF THE p-NITROPHENYLETHOXYCARBONYL GROUP FOR AMINO PROTECTION IN CYTIDINE AND ADENOSINE CHEMISTRY
Himmelsbach, Frank,Pfleiderer, Wolfgang
, p. 3583 - 3586 (2007/10/02)
Amino protection in 2'-deoxycytidine (1) and cytidine (2) as well as in 2'-deoxyadenosine (8) and adenosine (9) respectively can be achieved by the new reagents 1-(p-nitrophenylethoxycarbonyl)-benzotriazole (3) and 1-methyl-3-(p-nitrophenylethoxycarbonyl)-imidazolium chloride (7) to from the corresponding carbamates (4, 5, 13, 14) in high yields.
