Double diastereodifferentiation in the Mukaiyama aldol reactions of π-allyltricarbonyliron lactone complexes: 1,7- vs. 1,2-asymmetric induction

The Mukaiyama aldol reactions of trimethylsilyl enol ether-substituted π-allyltricarbonyliron lactone complexes with chiral aldehydes under BF3·OEt2 activation proceed with high levels of substrate control (1,7-induction), overriding possible 1,2-induction from the aldehyde stereogenic centre. When TiCl4 is used as the Lewis acid with (R)- or (S)-2-benzyloxypropanal, however, chelation control (1,2-induction) is observed, overriding the templating effect of the iron complex.