[newgradstud]

Hello everyone, I am trying to repeat this experiment but firstly I am trying to understand the mechanism of the reaction. I understand that the n-buli abstracts the proton from the oxadiazole ring making an (anion) organololithium reagent, but I am not sure of the purpose of Magnesium bromide ethyl etherate in this reaction. Initially, I thought it is probably acting as a lewis acid to activate the carbonyl of the aldehyde - however every similar procedure I have looked up on reaxys, uses Magnesium bromide ethyl etherate and no other LA for a substitute (eg TiCl4). Secondly, the reagent is added before adding the aldehyde therefore I am thinking if it makes a grinard reagent. But I cannot understand in this scenario what the grinard reagent is able to do that the organilithium can't.

Thoughts?

J. Med. Chem. 2001, 44, 8, 1268–1285