in the course on enantioselective organocatalysis, we discussed the route to hexoses via organocatalytic aldol addition and subsequent Mukaiyama addition. The use of either TiCl4 or MgBr2 leads to different products. Apparently this is due to either the cyclic or open transition state. However the information I can find on the transition state of the Mukaiyama is unsatisfying, and it is impossible for me to answer the following questions: Why are there different transition states for MgBr2 and TiCl4? How do they look? How is the stereochemistry affected, and how can I see this in the transition state?
I attached a screenshot of the presentation slide regarding this problem. Thanks for any help in advance!
Best regards. :)
