139705-33-2

Upstream product

• 501-53-1 benzyl chloroformate 
• 40733-28-6 5'-tert-butyldimethylsilyloxy-2'-deoxythymidine 
• 137160-76-0 acetone O-(benzyloxycarbonyl)oxime 
• 50-89-5 thymidine 

Relevant academic research and scientific papers

Hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method

The invention provides a hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method. Various silyl ether protecting groups of nearly 50 kinds of substrates can be efficiently removed in 0.5-16 hours at room temperature by taking 0.02mol%-0.3mol% hafnium trifluoromethanesulfonate as a catalyst, a silyl ether protected hydroxyl compound as a substrate and conventional AR methanol as a solvent. 42 kinds of silyl ether protecting group removing products can be obtained at high yield by performing conventional slica column chromatography purification on a crude product. By regulating the use amount of the catalyst, the Hf(OTf)4 catalyst can realize regioselective removal of 1-degree, 2-degree and 3-degree alkyl TBS and aryl TBS protective groups. Moreover, in a proper equivalent scope, the Hf(OTf)4 catalyst can also realize 1) chemoselective removal of different kinds of silica-based protective groups; and 2) chemoselective removal of 1-degree TBS protective groups under the condition of not affecting a majority of common hydroxyl protective groups.

Hafnium Triflate as a Highly Potent Catalyst for Regio- and Chemoselective Deprotection of Silyl Ethers

As a Group IVB transition metal Lewis acid, hafnium triflate [Hf(OTf) 4 ] exhibited exceptionally high potency in desilylations. Since the amounts of Hf(OTf) 4 required for the deprotection of 1°, 2°, 3° alkyl and aryl tert -butyldimethylsilyl (TBS) ethers are significantly different, ranging from 0.05 mol% to 3 mol%, regioselective deprotection of TBS could be easily implemented. Moreover, chemoselective cleavage of different silyl ethers or removal of TBS in the presence of most hydroxyl protecting groups was also accomplished. NMR analyses of silyl products from TBS deprotection indicated that Hf(OTf) 4 -catalyzed desilylation may proceed via different mechanisms, depending on the solvent used.

Facile deprotection of O-Cbz-protected nucleosides by hydrogenolysis: An alternative to O-benzyl ether-protected nucleosides

(Chemical Equation Presented) Because of side-reactions encountered during hydrogenolysis, benzyl ethers are usually not an effective protecting group for nucleosides. Benzyloxycarbamates provide an alternative to traditional benzyl ethers for protection of nucleoside hydroxyl groups, as they are much more labile to hydrogenolysis. Deprotection conditions using transfer hydrogenolysis are described that avoid the reduction of the pyrimidine nucleobase during deblocking of O-Cbz-protected nucleosides. Additionally, an experiment is described that suggests the nucleobase component of a nucleoside is responsible for the sluggish hydrogenolysis of nucleosides.

Lipase-mediated Alkoxycarbonylation of Nucleosides with Oxime Carbonates.

5'-O-Carbonates of ribonucleosides and 2'-deoxyribonucleosides could be obtained by enzymatic alkoxycarbonylation with SP 435 lipase (from Candida antarctica) and oxime carbonates, which are easily prepared from chloroformates.Ribonucleosides gave as resu