Background: Ursodeoxycholic acid is an important clinical drug in the treatment of liver disease. In our previous work, ursodeoxycholic acid was prepared by electroreduction of 7-ketolithocholic acid. The separation of ursodeoxycholic acid from the electroreduction product (47% (w/w) ursodeoxycholic acid) by silylation crystallization is described herein. Results: N,N-dimethylformamide was used...

1,1’-(ethane-1,2-diyl)dipyridinium bistribromide (edpbt) was used as a chemoselective and effective organocatalyst for the silylation of hydroxyl groups as well as desilylation of trimethylsilyl ethers under mild conditions at room temperature with good to excellent yields.

The combination of a boronic acid and a Lewis base, both employed in substoichiometric amounts, enables the regioselective silylation of cis-diol groups in alkylpyranoside substrates. The proposed mode of activation involves the formation of a tetracoordinate adduct that displays enhanced nucleophilicity at the boron-bound alkoxide groups.

In the presence of Rh(2)(OAc)(4) (OAc = acetate) and TBA(2)WO(4) (TBA = tetra-n-butylammonium), the N-silylation of indole derivatives with hydrosilanes efficiently proceeded to give the corresponding N-silylated indoles in high yields. Pyrrole and carbazole were also N-silylated with the combined catalysts.

Gettin' a little sugar-no alcohol required: A procedure for the direct glycosylation of ketones without a hydroxy intermediate enables the site-selective glycosylation of hydroxyketones at the ketone or the alcohol functionality without the use of protecting groups on the aglycone (see scheme). Site selectivity is controlled by the catalyst structure in hydrosilylation and dehydrogenative silyl...

Mesopore walls of hierarchically meso-/microporous zeolites (MFI, BEA and LTA) are covered with silanol groups, so that the zeolites can be functionalized with various organic groups via silylation; the organic-functionalized hierarchical zeolites exhibit hydrothermal stability and reusability in catalytic applications, as compared with organic-functionalized mesoporous silica.

The stereoselective synthesis of 3-substituted and 3,4-disubstituted piperidine and piperidin-2-one derivatives was achieved starting from 2-pyridone. After N-galactosylation and subsequent O-silylation, nucleophilic addition of organometallic reagents proceeded with high regioand stereoselectivity at 4-position. Substituents at position 3 were stereoselectively introduced by reaction of electr...

Certain (Z)-1,5-syn-diols 2 may be converted into 2,6-trans-5,6-dihydropyrans by using phosphonium salt 4 or phosphorane 5 as dehydrating agents. A more general four step procedure converts the (Z)-1,5-syn-endiols into enantiomeric dihydropyrans ent-3 via regioselective silylation of the allylic alcohol unit followed by mesylate formation and base-promoted nucleophilic displacement.

in this research, different alcohols and phenols are subjected to the reaction with hmds in the presence of ionic liquid and silica-supported catalysts. silylation was accomplished under mild reaction conditions at room temperature in short reaction times and good to excellent yields.