lithium hexamethyldisilazane; yttrium (III) trifluoromethanesulfonate in hexane; toluene T=0°C; 18 h;

1: With titanium tetrachloride in dichloromethane T=-78 - -50°C; Mukaiyama reaction; 2: With ammonium chloride T=-50 - 0°C; Title compound not separated from byproducts;