Efficient, Diastereoselective Chemical Synthesis of a β-Mannopyranosyl Phosphoisoprenoid
作者:David Crich、Vadim Dudkin
DOI:10.1021/ol006725p
日期:2000.11.1
[reaction: see text] Tetrabutylammonium benzyl dihydrophytylphosphate was coupled to S-phenyl 2,3-di-O-benyl-4, 6-O-benzylidene-1-thio-alpha-D-mannopyranoside S-oxide on activation with triflic anhydride in toluene at -78 degrees C to give the corresponding beta-mannosyl phosphate in 56% yield with no detectable formation of the alpha-anomer. Treatment with sodium in liquid ammonia then afforded the
Phosphorofluoridate analogues, of myo-inositol 1,4,5-tris(phosphate), 4-and 5-phosphorofluoridate and 4,5-bis(phosphorofluoridate), were prepared and their biological acivity towards InsP3 5-phosphatase was found to be similar to or more activ than that for InsP3 while they proved to be less active in the binding assay than InsP3.
Synthesis of the Fully Phosphorylated GPI Anchor Pseudohexasaccharide of <i>Toxoplasma </i><i>g</i><i>ondii</i>
作者:Klaus Pekari、Denis Tailler、Ralf Weingart、Richard R. Schmidt
DOI:10.1021/jo015840q
日期:2001.11.1
stereoselectivity and good yields in the glycosylation reactions, anchimeric assistance was employed. To enable regioselective attachment of the two different phosphorus esters, the 6f-O-silyl group of 32 was first removed and the aminoethyl phosphate residue was attached. Then the MPM group was oxidatively removed, and the second phosphate residue was introduced. Unprotected 1a was then liberated in two steps:
Inosine derivatives bearing a phosphodiester group at the O6-position of the nucleobase were synthesized via phosphitylation of the carbonyl oxygen using phosphoramidites activated by non-nucleophilic acidic activators.
The present invention provides nucleosides and oligonucleotides comprising a 5′ phosphate mimics of formula (IVc) or (Vc),
One aspect of the present invention relates to modified nucleosides and oligonucleotides comprising such dinucleotide of formula (Ia). Another aspect of the invention relates to a method of inhibiting the expression of a gene in call, the method comprising (a) contacting an oligonucleotide of the invention with the cell; and (b) maintaining the cell from step (a) for a time sufficient to obtain degradation of the mRNA of the target gene.