71009-10-4Relevant academic research and scientific papers
Hafnium Triflate as a Highly Potent Catalyst for Regio- and Chemoselective Deprotection of Silyl Ethers
Zheng, Xiu-An,Kong, Rui,Huang, Hua-Shan,Wei, Jing-Ying,Chen, Ji-Zong,Gong, Shan-Shan,Sun, Qi
, p. 944 - 953 (2019/02/10)
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.
Hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method
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Paragraph 0021; 0022, (2019/01/21)
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.
Gonadotropin Releasing Hormone Receptor Antagonist, Preparation Method Thereof And Pharmaceutical Composition Comprising The Same
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, (2013/06/05)
Disclosed are compounds useful as gonadotrophin-releasing hormone (“GnRH”) receptor antagonist.
The catalytic performance of Ru-NHC alkylidene complexes: PCy3 versus pyridine as the dissociating ligand
Krehl, Stefan,Geissler, Diana,Hauke, Sylvia,Kunz, Oliver,Staude, Lucia,Schmidt, Bernd
supporting information; experimental part, p. 1188 - 1198 (2011/03/23)
The catalytic performance of NHC-ligated Ru-indenylidene or benzylidene complexes bearing a tricyclohexylphosphine or a pyridine ligand in ring closing metathesis (RCM), cross metathesis, and ring closing enyne metathesis (RCEYM) reactions is compared. While the PCy3 complexes perform significantly better in RCM and RCEYM reactions than the pyridine complex, all catalysts show similar activity in cross metathesis reactions.
Efficient and chemoselective cleavage of TBS ethers by a sub-stoichiometric amount of decaborane
Jeong, Yeon Joo,Lee, Ji Hee,Park, Eun Soo,Yoon, Cheol Min
, p. 1223 - 1225 (2007/10/03)
TBS ethers od aliphatic alcohols in THF-MeOH (or methanol) were deprotected chemoselectively to the corresponding alcohols using a sub-stoichiometric amount of decaborane at rt under nitrogen in high yields.
Wang p-alkoxyphenylsulfoxide as a new linker and Pummerer cleavage strategy in solid-phase preparation of 1,2-diols
Rolland, Catherine,Hanquet, Gilles,Ducep, Jean-Bernard,Solladié, Guy
, p. 7563 - 7566 (2007/10/03)
para-Hydroxyphenyl-β-ketosulfide was attached to a Wang resin and oxidised to the corresponding sulfoxide with a N-protonated oxaziridinium trifluoroacetate. Reduction of the β-ketosulfoxides to the corresponding β-hydroxysulfoxides with Dibal-H was shown to be as stereoselective as in solution. Finally it was shown that the Pummerer reaction could be carried out on solid-phase and was a very efficient way to obtain diols that validates the sulfoxide group as a versatile linker for solid-phase chemistry.
An Investigation on Desilylation of Alkyl and Phenolic Silyl Ethers Using FeCl3
Saravanan, Parthasarathy,Singh, Vinod K.
, p. 565 - 567 (2007/10/03)
A variety of alkyl and phenolic TBDMS ethers have been efficiently cleaved using anhydrous FeCl3 in MeOH under mild conditions. It was found that choice of solvent is crucial for the rate of the deprotection of TBDMS ether with FeCl3.
Acid-catalyzed solvolysis of polyenol ethers. III. Effect of the alkoxy moiety
Nieuwenhuis, Saskia A. M.,Vertegaal, Louis B. J.,De Zoete, Marian C.,Van Der Gen, Arne
, p. 13207 - 13230 (2007/10/02)
The dependence of the solvolysis of polyenol ethers on the nature of the alkoxy moiety has been studied. A new reaction path, leading to the formation of ω-hydroxy (methoxy) substituted aldehydes and -esters, was established. The proposed reaction pathway (scheme 6) is initiated by an electron transfer from the polyenol ether to molecular oxygen, followed by combination of the two radicals to a peroxide zwitterion. Upon protonation, solvent adds to the ω-carbon atom of the polyene to give an intermediate that can either loose water to form an ester, or loose the alkoxy moiety to give an aldehyde. This mechanism is believed to be involved in the strong mutagenic activity displayed by many polyenol ethers, including the natural mutagen fecapentaene-12.
The Utility of t-Butyldimethylsilane as an Effective Silylation Reagent for the Protection of Functional Groups
Yamamoto, Keiji,Takemae, Makoto
, p. 2111 - 2113 (2007/10/02)
Treatment of compounds containing functional groups, such as alcohols, amines, and carboxylic acids, with t-butyldimethylsilane in the presence of a catalytic amount of palladium on carbon is described to provide a new, convenient method for the introduction of a t-butyldimethylsilyl (TBDMS) group.
