Diethyl ether terminal activation

Asymmetric epoxidation of a,jS-unsaturated ketones represents an efficient method for the preparation of optically active a,jS-epoxy ketonesJ Recently, a new and very efficient catalytic system for enantioselective epoxidation of ( )-a,jS-enones to the corresponding trans-epoxy ketones has been developed based on a BlNOL-zinc complexJ Very high yields and excellent diastereo- and enantioselectivities are achieved at room temperature using cumene hydroperoxide (CMHP) as the terminal oxidant and performing the reaction in diethyl ether. A combination of enantio-merically pure BINOL and diethylzinc readily affords the active catalyst in situ (Figure 6.13). ... 

Recently we presented a new methodological approach for catalytic sulfoxidation which makes use of water as solvent in the presence of anionic surfactant, and hydrogen peroxide as terminal oxidant activated by an easily prepared chiral Pt(ll) complex, all under mild conditions (Figure 9.7). Moreover, the enantioenriched sulfoxides are isolated from the catalyst by means of simple diethyl ether extraction (Figure 9.8) which does not dissolve the catalyst. 

Peptide C-Terminal Deprotection and Activation. Glycopeptide 21 was obtained by repeated -terminal deprotection and coupling to amino acids. A part of 21 (5 mg, 0.005 mmol) was dissolved in 20% TFA in DCM (2 mL), and the solution was stirred at room temperature for 2 h. The reaction mixture was diluted with toluene (4 mL) and concentrated to dryness in vacuum. The residue was then dissolved in H20 (5 mL). After washed with diethyl ether (5 mL) twice, the aqueous solution was lyophilized to afford a white solid. Upon its dissolution in NMP (1 mL), pentafluorophenol (9 mg, 0.05 mmol) and DCC (21 mg, 0.1 mmol) were added, and this homogeneous solution was stirred at room temperature for 5 h. The reaction mixture was diluted with diethyl ether (10 mL), and the resultant precipitate was isolated and washed as described above to give 22 as a wet white solid. 

Dodecylbenzyldiethylsulfonium Chloride. Into a 500 ml flask was added 76.6 g (0.200 moles) of- practical grade p-dodecylbenzyl chloride, 26.5 g (0.294 moles) diethyl sulfide (Eastman White label), 200 gof methanol and 2 g deionized water. Stirring was started and after 218.5 hrs the reaction was terminated by extracting it 3 times with 125 ml portions of a 50/50 (vol/vol) n-hexane/ether mixture. The aqueous fraction was separated and concentrated under vacuum to give 429 g of solution which was 19.8% active. The conversion was 85%. 

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