page3%20amend%2015092008 - CEM 850 B Alcohol Protection...

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CEM 850 3 B. Alcohol Protection continued (15 September 2008) Benzylic Ethers Reagents, solvent PG Reagent Product Deprotection ROH NaH/THF Ph Br H acidic proton, BuLi sensitive Ph OR Hydrogenolysis (Pd/C, H 2 , EtOH) 2°, 3° slow to hydrog. HO R R DIPEA/DCM Ph O Cl benzyloxychloromethane Ph O O R R Pd(OH) 2 , H 2 , EtOH Pearlman's cat. O H 3 C O OH Base sensitive cpd TfOH NH OP h C Cl 3 benzyltrichloroacetimidate O H 3 C O O Ph Hydrogenolysis cond'ns ROH TEA, DMAP. (or DABCO) N N 1,4-diazabicyclo[2.2.2]octane Cl O O Less stable to acid than benzyl (WHY?) DDQ, CH 2 Cl 2 , H 2 O O O Cl Cl NC 2,3-dichloro-5,6- dicyanoquinone Trityl Ethers H 3 C O OH TEA, DMAP, DCM Ph 3 CCl HCOOH or Pd/C, H 2 Trityl salts Silyl Ethers R'OH Imid, TEA, DMAP, DBU, or 2,6- lutidine N N N (hindered ROH, use NaH, MeLi,
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This note was uploaded on 09/22/2008 for the course CEM 850 taught by Professor Borhan during the Spring '05 term at Michigan State University.

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