Procedure:  1000 mL 1-neck flask, stirbar, septum, N₂ inlet

                  Dissolved 17.966 g of alcohol I in 400 mL of dry CH₂Cl₂.  Stirred at rt.  Added 19.10 mL of Ac₂O followed by 22.6 mL of Et₃N and 0.469 g of DMAP.  After 3h, quenched with sat. aq. NH₄Cl.  Extracted with CH₂Cl₂.  The organic layer was dried over MgSO₄, filtered and the solvent was removed by rotary evaporation.  The product was isolated by flash chromatography on silica gel using 10:90 EtOAc-hexanes as eluant.  The product was a clear, colorless oil. 

 

[a]_D +11.00 (c = 1.82, CH₂Cl₂).

 

notes

 

In this reaction an acyl pyridium ion is formed which is the reactive species.  Facile addition of the alcohol to the acyl pyridinium ion regenerates DMAP and, after loss of the oxonium proton to acetate, forms the desired product plus acetic acid which is scavenged by Et₃N.