Cationic organotin clusters for highly efficient alcohol acetylation catalysts

The effectiveness of cationic species for increasing the catalytic activity of organotin Lewis acids has been assessed by comparing two types of catio nic organotin clusters, [Bu2Sn(OH)-(H2O)](2)(2+)2OTf(-) and [(BuSn)(12)O-14 (OH)(6)]Cl-2+(2)-.2H(2)O, with neutral clusters in alcohol acetylation. The Sn-2 dication is extremely active, with a catalyst concentration of 0.001 mol %, sufficient to give a quantitative yield. The Sn-12 dication is sligh tly less active but gives high levels of chemoselectivity and primary/secon dary alcohols selection. The neutral clusters are less effective catalysts. A variety of synthetic applications are feasible by changing the Lewis aci dity of the catalysts.