TBDMS ethers

NBS, CH3CN, H2O, 62-90% yield.The POM group has been selectively removed in the presence of an ethoxy ethyl ether, TBDMS ether, benzyl ether, p-methoxybenzyl ether, an acetate, and an allyl ether. Because the hydrolysis of a pentenyl 2-acetoxyglycoside was so much slower than a pentenyl 2-benzyloxyglycoside, the 2-benzyl derivative could be cleaved selectively in the presence of the 2-acetoxy derivative. The POM group is stable to 75% AcOH, but is cleaved by 5% HCl. 

Dichlorodicyanoquinone (DDQ), CH2CI2, H2O, 40 min, it, 84-93% yield.This method does not cleave simple benzyl ethers. This method was found effective in the presence of a boronate. The following groups are stable to these conditions ketones, epoxides, alkenes, acetonides, to-sylates, MOM ethers, THP ethers, acetates, benzyloxymethyl (BOM) ethers, and TBDMS ethers. 

The triethylsilyl ether is approximately 10-100 times more stable than the TMS ether and thus shows a greater stability to many reagents. Although TMS ethers can be cleaved in the presence of TES ethers, steric factors will play an important role in determining selectivity. The TES ether can be cleaved in the presence of a /-butyldimethylsilyl ether using 2% HE in acetonitrile. In general, methods used to cleave the TBDMS ether are effective for cleavage of the TES ether. 

AcOH, H2O, THE. Any of the methods used to cleave the TBDMS ether also cleave the DEIPS ether. 

Selective cleavage of one secondary TBDMS ether in the presence of a somewhat more hindered one was achieved with Bu4N F in THF. ... 

AC2O, CH2CI2, 15 kbar (1.5 GPa), 79-98% yield. This high pressure technique also works to introduce benzoates and TBDMS ethers onto highly hindered tertiary alcohols. 

AC2O, FeCl3, It, <30 min, 60-93% yield. These conditions will selectively protect an aldehyde in the presence of a ketone. This combination also converts r-butyldimethylsilyl (TBDMS) ethers to acetates. 

Catecholborane halide cleaves benzyl carbamatesi in the presence of ethyl and benzyl esters and TBDMS ethers." ... 

MgBr2, n-BuSH, Et20, rt, 3-24 h, 49-97% yi ld. MOM and MTM ethers are also cleaved, but MEM and TBDMS ethers are stable. These conditions have resulted in the formation of an ethyl thioether. " ... 

MeOH, reagent prepared by heating Bu2SnO and Bu3SnP04, heat 2 h, 90% yield." This method is effective for primary, secondary, tertiary, benzylic, and allylic THP derivatives. The MEM group and ketals are inert to this reagent, but TMS and TBDMS ethers are cleaved. 

TBDMSOTf, CH2CI2 Me2S, 95% yield. The THP group is converted directly into a TBDMS ether." ... 

CAN, MeOH, 0°, 0.5-3 h, 81-95% yield. TBDMS ethers are more easily cleaved thus, a TBDMS ether is cleaved selectively in the presence of a THP ether (15 min, 95%). ... 

BF3-Et20, HSCH2CH2SH, CH2CI2, 100% yield. A primary TBDMS ether was not affected. ... 

N HCl, THE, 0°, 100% yield. The ethoxyethyl ether is more readily cleaved by acidic hydrolysis than the THP ether, but it is more stable than the 1-methyl-1-methoxyethyl ether. TBDMS ethers are not affected by these conditions. ... 

TBDMSOTf, CH2CI2, rt, 24 h, 82% yield. The use of a catalytic amount of the triflate will give the alcohol. If the triflate is used stoichiometrically and the reaction worked up with 2,6-lutidine, the TBDMS ether is isolated (98% yield). "... 

TBDMSOTf, TEA, CH2CI2, rt. These conditions result in conversion of the MPM ether into a TBDMS ether. 

MgBr2-Et20, Mc2S, CH2CI2, it, 75-96% yield. " The failure of this substrate to undergo cleavage with the typical conditions was attributed to the presence of the 1,3-diene. Acetonides and TBDMS ethers were found to be stable. 

BCI3, CH2CI2, -10°, 20 min. then cold NaHC03. TBDMS ethers were stable to these conditions. 

NH4 F, MeOH, H2O, 60-65°, 65% yield. Selectivity for primary TBDMS ethers has been observed with this reagent. ... 

PdO, cyclohexene, methanol, 30 min for a primary ROH, 90-95% yield. Secondary alcohols require longer times. The primary TBDPS and TIPS groups are cleaved much more slowly (18-21 h). Benzylic TBDMS ethers are cleaved without hydrogenolysis. ... 

AcBr, CH2CI2, it, 20 min, 90% yield. These conditions convert the TBDMS ether into the acetate. Benzyl and TBDPS ethers are stable, except when SnBr2 is included in the reaction mixture, in which case these groups are also converted to acetates in excellent yield. ... 

BF3 Et20)-Bu4N F. This reagent is selective for TBDMS ethers in the presence of TIPS and TBDPS ethers. ... 

During an attempt to metalate a glycal with /-BuLi, it was discovered by deuterium labeling that a TBDMS ether can be deprotonated. °- ... 

DMSO, H2O, 90°, 79-87% yield. These conditions are only effective for primary allylic and homoallylic, primary benzylic, and aryl TBDMS ethers. ... 

The oxidative deprotection of silyl ethers, such as the TBDMS ether, has been reviewed. " ... 

Photolysis at 254 nm, CH3OH, CH2CI2, phenanthrene, 51-84% yield. These conditions are selective for ally lie and benzylic alcohols. In the absence of the phenanthrene, TBDMS ethers are also cleaved. ... 

NajS HjO, EtOH, rt, 12-72 h, 70-100% yield. TBDMS ethers are stable to these conditions. 

The section on alcohol protection should be examined, since many of the methods for the formation and cleavage of TBDMS ethers are similar. 

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