- Improved syntheses of d-ribo- and 2-deoxy-d-ribofuranose phospho sugars from methyl β-d-ribopyranoside
-
Abstract - Methyl 4-deoxy-4-dimethoxyphosphinoyl-2,3-O-isopropylidene-13-D-ribopyranoside (12a) and methyl 2,4-dideoxy-4-dimethoxyphosphinoyl-13-D-etythro-pentopyranoside (20) were efficiently prepared respectively from methyl2,3-O-isopropylidene-[3-D-rib
- Hanaya, Tadashi,Koga, Yuko,Kawamoto, Heizan,Yamamoto, Hiroshi
-
scheme or table
p. 581 - 591
(2009/09/08)
-
- An efficient stereoselective synthesis of the amino sugar component (E ring) of calicheamicin γ1(I)
-
A simple, efficient, stereoselective synthesis of the methyl 2,4-dideoxy-4-(ethylamino)-3-O-methyl-β-L-threo-pentopyranoside 2, corresponding to the E monosaccharide unit (E ring) of calicheamicin 1, is described. The synthetic procedure utilizes the methyl 2-deoxy-β-D-ribopyranoside 3 as the enantiopure starting material and the acid methanolysis of the intermediate activated aziridine 12 to give the desired amino sugar 2 in 6 steps and in satisfactorily high overall yield (60%). No separation stage is necessary at any point of the synthetic process.
- Crotti,Di Bussolo,Favero,Macchia,Pineschi
-
p. 779 - 786
(2007/10/03)
-
- 4'-Thionucleosides via in situ pyranose-furanose rearrangements: A short synthesis of the antiherpes agent 2'-deoxy-5-ethyl-4'-thiouridine via direct coupling of a silylated pyrimidine base with a 4-thiopyranose sugar
-
Methyl 2-deoxy-3,4-O-thiocarbonyl-β-D-ribopyranoside was converted into the thione carbonate by reaction with thiophosgene. Bromide ion-catalyzed O-S rearrangement produced methyl 2-deoxy-3-O,4-S-carbonyl-4-thio-β-D- ribopyranoside (3a) and the 3-O,4-S isomer 3b. The carbonates were cleaved with ammonia and the 3-O,4-S pyranoside sugar coupled with bis(trimethylsilyl)-5-ethyluracil using trimethylsilyl triflate to provide the antiherpes agenet 2'-deoxy-5-ethyl-4'-thiouridine 9. The reaction proceeded via in situ pyranoside rearrangement of the sugar and subsequent coupling. The pyranoside sugar could also be converted to the furanoside form with Dowes H+ acid resin and coupled in conventional fashion to give the nucleoside. Coupling of methyl 4-O-carbamoyl-2-deoxy-3-thio-β-D- ribopyranoside (4b) with the bis(trimethylsilyl)-5-ethyluracil gave 1-[2-[2- (hydroxymethyl)thiiran-1-yl]-1-methoxyethyl]-5-ethyluracil.
- Jandu,Selwood
-
p. 5170 - 5173
(2007/10/02)
-
- METHYL ETHERS OF METHYL 2-DEOXY-α- AND β-D-threo-PENTOPYRANOSIDE
-
Methyl 2-deoxy-α- and β-D-threo-pentopyranosides (Ia, IIa) were prepared.Various conditions for partial methylation of the β-anomer IIa were tried out, leading to methyl 2-deoxy-3-O-methyl-β-D-threo-pentopyranoside (IIc), methyl 2-deoxy-4-O-methyl-β-D-threo-pentopyranoside (IId) and methyl 2-deoxy-3,4-di-O-methyl-β-D-threo-pentopyranoside (IIe).The structures of the products were determined by means of 1H NMR.
- Medonos, Ivan,Kocikova, Veroslava,Stanek, Jan,Zobacova, Alena,Jary, Jiri
-
p. 1671 - 1677
(2007/10/02)
-