MECHANISM OF THE MUKAIYAMA ALDOL REACTION - THE 1ST SOLID-STATE CHARACTERIZATION OF A TRICHLOROTITANIUM ALDOLATE

The reaction of the silyl ketene acetal Me2C=C(OMe)OSiMes (1) with preformed TiCl4 carbonyl adducts (the monomeric [PhC(O)C(O)PhTiCl4] (2) and the dimeric {[MesCHOTi(Cl)3]2(mu-Cl)2} (Mes = 2,4,6-Me3C6H2; 3)) led to the isolation and structural characterization of the corresponding titanium aldolate complexes {[(PhCO)PhC(O)C(Me2)C(OMe)OTi(Cl)2]2(mu-Cl)2} (4) and {[MesCH(O)C(Me2)C(OMe)OTi(Cl)2]2(mu-Cl)2} (5), in which the aldolate fragment functions as a bidentate ligand in dimeric titanium complexes bridged by two chlorine atoms. Crystallographic details: 4 is monoclinic, space group P2(1)/n, with a = 9.029(1) angstrom, b = 17.468(2) angstrom, c - 13.165(2) angstrom, beta = 98.81(2)-degrees, Z = 2, and R = 0.53.