US EPA

7484608 

Journal Article 

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

Zheng, XA; Kong, R; Huang, HS; Wei, JY; Chen, JZ; Gong, SS; Sun, Q 

2019 

1 

Synthesis
ISSN: 0039-7881
EISSN: 1437-210X 

Georg Thieme Verlag 

51 

4 

944-953 

English 

10.1055/s-0037-1610307 

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. © Georg Thieme Verlag Stuttgart - New York. 

chemoselectivity; desilylation; hafnium triflate; mechanism; regioselectivity; Ethers; Hafnium; Mechanisms; Regioselectivity; Chemo-selectivity; Chemoselective deprotection; Desilylation; Different mechanisms; Protecting group; Regio-selective; Tert-butyldimethylsilyl; Triflates; Hafnium compounds; (2 [[tert butyldimethylsilyl]oxy]phenyl)methanol; (4 [acetoxymethyl]phenyl)methanol; (4 [tetrahydro 2h pyran 2 yloxymethyl]phenyl)methanol; (4 [trityloxymethyl]phenyl)methanol; (4 [[2 methoxyethoxy]methoxymethyl]phenyl)methanol; (4 [[4 methoxybenzyloxy]methyl]phenyl)methanol; (4 [[[tert butyldimethylsilyl]oxy]methyl]phenyl)methanol; (4 [[[tert butyldiphenylsilyl]oxy]methyl]phenyl)methanol; (4 [[[triisopropylsilyl]oxy]methyl]phenyl)methanol; 2 ([tert butyldimethylsilyl]oxy) 2 phenylethanol; 2',3' (tert butyldimethylsilyl)uridine; 2,3 o isopropylidene beta dextro ribofuranosyl 1 azide; 3 ([tert butyldimethylsilyl]oxy) 3 methylbutan 1 ol; 3' o (benzyloxycarbonyl)thymidine; 3' o (tert butyldimethylsilyl)thymidine; 4 (2,2 dimethyl 1,3 dioxolan 4 yl)butan 1 ol; 4 ([tert butyldimethylsilyl]oxy) 4 methylpentan 2 ol; 6 (allyloxy)hexan 1 ol; 6 (methoxymethoxy)hexan 1 ol; 9h fluoren 9 ylmethyl 2 ([tert butyldimethylsilyl]oxy) 3 hydroxypropylcarbamate; benzyl 3,4 o isopropylidene beta levo arabinopyranoside; hafnium triflate; hydroxyl group; methyl 3,4 o isopropylidene beta levo arabinopyranoside; silane derivative; tert butyl 2 (4 [[tert butyldimethylsilyl]oxy]phenyl) 2 hydroxyethyl(methyl)carbamate; tert butyl 2 ([tert butyldimethylsilyl]oxy) 3 hydroxypropylcarbamate; tert butyldimethylsilyl ether; trifluoromethanesulfonic acid; unclassified drug; Article; catalyst; chemical analysis; chemical reaction; chemical structure; controlled study; deprotection reaction; desilylation; nuclear magnetic resonance spectroscopy; reaction time; regioselectivity; synthesis