formaldehyd; boron trifluoride diethyl etherate; toluene-4-sulfonic acid 1.) acetone, water, rt, 4 h; 2.) rt, 15 h; Yield given. Multistep reaction;

1: 1.) p-toluenesulfonic acid, paraformaldehyde; 2.) BF3*Et2O / 1.) acetone, water, rt, 4 h; 2.) rt, 15 h 2: 90 percent / 1percent NaOH / diethyl ether; H2O / 72 h View Scheme