[en] The temperature dependence from -78 to +25⁰ of the isotope effect in the asymmetric Grignard reductions of phenyl trifluoromethyl ketone with (S)-1,1,2-trideuterio-2-phenylethyl-magnesium bromide and (R)-2-deuterio-2-phenylethyl-magnesium bromide, prepared from (R)-(-)-mandelic acid, was studied. In addition the isotope effect and stereoselectivity of the asymmetric Meerivein-Ponndorf-Verley (MPV) reductions of 1 with (R)-neopentyloxy-1-d-magnesium bromide at 18⁰ and (S)-benzyloxy-1-d-magnesium bromide at 22⁰ were investigated