Oliver Schulze

Preparation of selenoanhydro- and telluroanhydroglycofuranosides and some corresponding nucleosides.

Methyl 2,3-anhydro-alpha-D-ribofuranoside (3a) was transformed into methyl 2-seleno-2,5-anhydro-alpha-D-arabinofuranoside (5a) and methyl 3-seleno-3,5-anhydro-alpha-D-xylofuranoside (6a) in two steps via the reaction of the C-5 mesylate of 3a, methyl 2,3-anhydro-5-O-mesyl-alpha-D-ribofuranoside (4a), with sodium hydrogen selenide. The corresponding beta anomer of 3a yielded methyl 3-seleno-3,5-anhydro-beta-D-xylofuranoside as the main product and only traces of methyl 2-seleno-2,5-anhydro-beta-D-arabinofuranoside. Sodium hydrogen telluride transformed 4a into methyl 2-telluro-2,5-anhydro-alpha-D-arabinofuranoside. Starting from 5a we prepared 1-(2-seleno-2,5-anhydro-alpha-D-arabinofuranosyl)uracil and the analogous thymidine nucleoside. Compound 6a could not be transformed into nucleosides.

The thio-Mitsunobu reaction of D-glucitol, D-mannitol, galactitol and 1-seleno-D-xylitol.

Unprotected D-glucitol is transformed into 5-O-acetyl-1,4-anhydro-6-thio-D-glucitol (3) in one step by use of the thio-Mitsunobu reaction. Rearrangement (acetyl group migration) to form 3-O-acetyl-1,4-anhydro-6-thio-D-glucitol occurs during column chromatography of 3 on silica gel. 2,5-Di-O-acetyl-1,6-dithio-D-mannitol and 1,6-di-S-acetyl-2,5-anhydro-1,6-dithio-D-glucitol (characterized as the corresponding p-nitrobenzoates) are formed from D-mannitol, whereas galactitol yields a mass of unidentified products. 1-Seleno-D-xylitol, produced by reduction of D-xylose with hydrogen selenide, does not undergo a Mitsunobu reaction.

Preparation and Reactions of 2-Oxa-6-thiabicyclo[3.2.0]-heptanes and 2-Oxa-5-thiabicyclo[2.2.1]heptanes from Pentoses

Abstract: The preparation of the two diastereoisomeric 3-methoxy-2-oxa-6-thiabicyclo-[3.2.0]heptan-4-ols 4 and 5 from D-xylose 1 via methyl 2,3-anhydro-α-D-ribofuranoside and the corresponding β-anomer is described. Oxidation of 4 and 5 yields the sulfoxides 6 and 7 and the sulfones 8. – On the other hand, the two diastereoisomeric 3-methoxybicyclo[2.2.1]heptan-7-ols 11 and 12 are obtained from methyl 5-acetylthio-5-deoxy-2-O-mesyl-D-xylofuranosides 9 and 10 via Mitsunobu reaction and intramolecular cyclization. – The stereoisomeric counterparts of 4 and 5, 13 and 14, are obtained in only four steps from L-arabinose.

Thiosugars. XII. Synthesis of New 3′‐O‐Substituted 2′,5′‐Anhydro‐2′‐thio‐α‐d‐pentofuranosyl Nucleoside Analogues

Methyl 2,5‐anhydro‐3‐O‐(2‐methoxyethyl)‐2‐thio‐β‐d‐arabinofuranoside and methyl 2,5‐anhydro‐3‐O‐(2‐fluorobenzyl)‐2‐thio‐α‐d‐lyxofuranoside were transformed into the corresponding uridine, thymidine, cytidine and adenosine analogues, which exclusively exhibited the α‐configuration irrespective of the anomeric configuration of the donor. The structure, configuration, and conformation of the products was elucidated by X‐ray structure analyses. The nucleoside analogues were tested for antiviral activities. #Part XI: See Ref. 11.

Synthesis and biological evaluation of isonucleosides derived from methyl 3,5-anhydro-2-O-(2-fluorobenzyl)-D-xylofuranosides.

Abstract New isonucleosides [methyl 5-(1-pyrimidinyl)furanosides] are prepared by nucleophilic opening of the oxetane ring of methyl 3,5-anhydro-2-O-(2-fluorobenzyl)-D-xylofuranoside with silylated pyrimidine bases in the presence of trimethylsilyl triflate. Structures, configurations and conformations were determined by NMR techniques and several X-ray diffraction analyses. seven of the isonucleosides were tested for cytotoxicity and activity against HIV, HSV and several other viruses.

The structure of McN-5652.

The configuration of the diastereoisomers of 6-(4-methylthiophenyl)-1,2,3,5,6,10b-hexahydropyrrolo[2,1-a]isoquinoline 1 (McN-5652) is determined and unequivocally assigned by NMR spectroscopy (NOE measurements) and an X-ray structural analysis of the trans diastereoisomer. The enantiomers of cis-1 are separated by preparative HPLC on a chiral phase. One of the enantiomers of cis-1 represents the precursor for imaging the serotonin 5-HT transporter with positron emission tomography (PET).

Stereoselective Preparation of Bicyclic Selena and Telluraheterocycles Starting from the Chiral Pool

The preparation of seleno- and telluroesters by way of the Mitsunobu reaction[1] is not possible since seleno- and telluroacetic acid are unsuitable reagents. However, sodium hydrogen selenide and telluride can be conveniently prepared as in situ reagents. These powerful nucleophiles readily attack methyl 2,3-anhydro-5-O-mesyl-α-D-ribo-furanoside (1) to yield in a tandem reaction the selena- (3) – (5) and tellurabicyclics (11) as pure enantiomers.