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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: kriggy on July 04, 2019, 06:54:03 AM

Title: Organocatalytic allylation of aldehydes/ketones/imines
Post by: kriggy on July 04, 2019, 06:54:03 AM

Hey guys,

im reading on the topic of organocatalytic allylation of carbonyl compounds using allyl trichlorosilane and while there is bunch of different chiral ligands for this transformation using for example chiral DMF analogues

Tetrahedron Lett. 1998, 39, 2767
or chiral pyridine-N-oxides

J. Am. Chem. Soc.1998120256419-6420

and Im wondering...
a) is there a reason why common BINOL is not used? I feel like there is a risk of it forming covalent bond with allyl-SiCl₃ but after reading 3 reviews, no mention was found.

b) Why imines seem to be less reactive for the allylation compared to aldehydes ? Maybe Im wrong on this one but I always thought imines are more reactive towards addition reactions compared to aldehydes...?

c) What could be a reason for catalyst that works perfectly fine for asymmetric reduction with HSiCl₃ give no reaction at all with allylSiCl₃ when the mode of activation should be the same (formation of hexacoordinated silicon) - this is related to my own work in a lab and Im bit struggling with it. We designed the catalyst for HSiCl₃ so this was just an random attempt to see if it works.