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Topic: n-BuLi/DMF formylation mechanism  (Read 13098 times)

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Offline ivanakaj

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n-BuLi/DMF formylation mechanism
« on: March 03, 2014, 05:06:35 AM »
I am in need of a mechanism of the lithiation reaction with n-BuLi on any heterocycle (i need oxazole, but any will do). and the mechanism of the subsequent formylation of the lithium-azole with dimethylformamide.
I would be very thankfull for a step by step mechanism if there is anybody willing to write it. Have been searching for one, but can't find nowhere.

I
« Last Edit: March 03, 2014, 05:31:34 AM by ivanakaj »

Offline sjb

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Re: n-BuLi/DMF formylation mechanism
« Reply #1 on: March 03, 2014, 06:32:11 AM »
Bu- removes the proton, then the anion formed attacks DMF. Over to you.

Offline ivanakaj

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Re: n-BuLi/DMF formylation mechanism
« Reply #2 on: March 03, 2014, 07:02:29 AM »
Yes...i need the mechanism of the both reaction. Mechanism of the first reaction , of lithiation is one that follows thorough a complex that forms between the n-Buli and N on the oxazole and directs the Li to position 2 on the oxazole ring. Ok, but the mechanism of the reaction after the carbanion attack on the DMF and the formation of subsequent intermediate? 

Offline TheUnassuming

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Re: n-BuLi/DMF formylation mechanism
« Reply #3 on: March 04, 2014, 04:52:58 PM »
So by forum rules no-one here is going to give you a written step-wise mechanism for any reaction, we can help you along but you have to put in the work. 
Yes, the oxazole is deprotonated at C2.  The N directing is helpful but its also the most acidic proton (K2CO3 is capable of deprotonating to a sufficient degree for a number of reactions to take place). 
If the oxazol(ium?) then attacks the aldehyde of DMF, what will likely happen next?
When in doubt, avoid the Stille coupling.

Offline ivanakaj

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Re: n-BuLi/DMF formylation mechanism
« Reply #4 on: March 20, 2014, 08:32:36 AM »
I worked out the entire step by step mechanism....thank you all for input....:)

Offline kamiyu

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Re: n-BuLi/DMF formylation mechanism
« Reply #5 on: March 25, 2014, 06:11:28 PM »
Note the formylation in this way always followed by acid hydrolysis.

Thus, the nucleophilic addition towards DMF forms only intermediate.

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