T-Butyldiphenylsilyl

Both benzyl ether, benzyloxymethyl and t-butyldiphenylsilyl protecting groups were removed on Pd(OH)2/C in methanol-acetone (Scheme 4.35).165... 

Scheme 5.2 (a) Monosaccharide building blocks 1-3 selected for solid phase synthesis of heptasaccharide 16 (b) attachment of the first carbohydrate onto phenolic polystyrene through a new photocleavable o-nitrobenzyl-type linker29 (Bn = benzyl, Bz = benzoyl, Fmoc = 9-fluoromethyloxycarbonyl, Ph = phenyl, py = pyridine, TBDPS =t-butyldiphenylsilyl). 

Allenyltrimethylsilanes add to ethyl glyoxalate in the presence of a chiral pybox scandium triflate catalyst to afford highly enantioenriched homopropargylic alcohols or dihydrofurans, depending on the nature of the silyl substituent (Tables 9.39 and 9.40) [62]. The trimethylsilyl-substituted silanes give rise to the alcohol products whereas the bulkier t-butyldiphenylsilyl (DPS)-substituted silanes yield only the [3 + 2] cycloadducts. A bidentate complex of the glyoxalate with the scandium metal center in which the aldehyde carbonyl adopts an axial orientation accounts for the observed facial preference ofboth additions. 

Methoxy-2-pyridyl 2,3,4-tri-0-p-fluorobenzoyl-6-0-(6-0-t-butyldiphenylsilyl a-D-glucopyranosyl)- -D-glucopyranostde... 

Glycosylation of 3-Methoxy-2-pyridyl 2,3,4-tri O-p-fluorobenzoyl-6-0-(2,3,4-tri-0-p-fluorobenzoyl-a.-D-glucopyranosyl)- -D-glucopyranoside (34) with 3-Methoxy-2-pyridyl-6-0-(6-0-t-butyldiphenylsilyl-a.-v-galactopyranosyl-)fi-D-galactopyranoside (31)... 

Methyl 2,3-di-O-benzyl-a-D-glucopyranoside t-Butyldiphenylsilyl chloride Tetrabutylammonium fluoride 2,2,6,6-Tetramethylpiperidine Potassium hydroxide Periodinane... 

To a stirred solution of methyl 2,3-di-0-benzyl-6-0-t-butyldiphenylsilyl-a-D-glucopyranoside (0.617 g, 1.01 mmol) in toluene (5 ml) was added 1,1 -thiocarbonyldiimidazole (0.359 g, 2.01 mmol) at room temperature. The solution was heated at reflux. The reaction mixture was poured into 0.5 N HCI (50 ml) and extracted with CH2CI2 (3x50 ml). The organic layers were combined, washed with sat. sodium bicarbonate solution followed by brine, dried over sodium sulfate and filtered. The solvent was removed in vacuum to give a crude yellow oil, which was purified by column chromatography over silica gel (hexane-EtOAc, 7 3) to afford 0.676 g (93%) of methyl 2,3-di-O-benzyl-6-0-t-butyldiphenylsilyl-4-0-imidazolyl-thiocarbonyl-a-D-glucopyranoside as a colorless viscous oil. 

Mulzer and Schollhorn showed that the reaction of triol monosilyl ether 279 with potassium carbonate gave a 6 7 87 mixture of 279, 280 and 281 at equilibrium (equation 176), indicating that the terminal primary position was favored as the location of the t-butyldiphenylsilyl (TBDPS) group. Similarly, 282 afforded 283 as a major migration... 

The chiral 2-butenylsilanes (5)-43 and (/ )-43 react with either the benzyl protected a-alkoxyaldehyde (S)-26 or the t-butyldiphenylsilyl protected a-alkoxyalde-... 

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