摘要:
3- O -Benzyl-6-deoxy-1,2- O -isopropylidene-alpha-d- xylo -hept-5- ulofuranurononitrile (1) was reacted with N , N -dimethylformamide dimethylacetal in tetrahydrofuran to furnish the ( E )-3- O -benzyl-6-deoxy-6-dimethylaminomethylene-1,2- O -isopropylidene-a-d- xylo -hept-5-ulofuranurononitrile (2) as a major product. Furthermore, treatment of compound 1 with carbon disulphide and methyl iodide under basic conditions afforded 3- O -benzyl-6-deoxy-1,2- O -isopropylidene-6-[bis(methylsulfanyl)methylene]-alpha-d- xylo -hept-5-ulofuranurononitrile (6). Reaction of 2 and 6 with hydrazines yielded the "reversed pyrazole- C -nucleoside analogs 4, 5a, 5b, 7, 8, and 9, respectively.