in tetrahydrofuran; hexane under Ar: reaction of CH2C(CH3)CH2MgCl in THF with SnCl4 in n-hexane (Mg:Sn = 6:1); heating under reflux for 5 h; addn. of 2 M HCl under ice-cooling;; drying the non-aq. phase with Na2SO4; distillation of solvent; distillation in vac.; elem. anal.;;

in methanol T=25°C;