A simple and scalable procedure for TiCl4-promoted aldol reaction

TiCl4-promoted aldol reaction was carried out by adding TiCl4 to a solution of the aldol reaction substrates and (i-Pr)2NEt (DIPEA) in CH2Cl2. Compared to the conventional order of addition (sequentially adding TiCl4, DIPEA, and piperonal to the lactone 2 in CH2Cl2), this simplified procedure, gave a much cleaner reaction that could be executed on large scale and without cryogenic cooling. However this procedure provided no stereoselectivity.