[jarritos]

 mw:276

Im having trouble finding a mechanism for this problem

This triazolium salt was treated with potassium tert-butoxide in THF and quenched into methanol resulting in 2 LC peaks with masses of 288. When the LC vials were quenched with THF and MeCN, those 2 peaks did not appear. When the reaction was quenched with ethanol, one peak with a mass of 302 appeared by LC. Propose possible structures and mechanism with masses of 288 and 302.

The mechanism is the difficult part which would lead you to the structure.

[jarritos]

I know the tert is a strong non-nucleophillic base and is known to be used in dehydrohalogenation reactions but I dont see how a F would be removed. Ive been toying with the mw as a first step to solving this. Adding a carbon would result in mw of 288. Its probably easier than it looks and its possibly just me and my lack of sleep.

[discodermolide]

I know the tert is a strong non-nucleophillic base and is known to be used in dehydrohalogenation reactions but I dont see how a F would be removed. Ive been toying with the mw as a first step to solving this. Adding a carbon would result in mw of 288. Its probably easier than it looks and its possibly just me and my lack of sleep.

This is displacement of the para F and the ortho F with methoxide, these are the 2 compounds with mass 288.
The other is displacement with ethoxide, probably the para F, to give a compound with mass 302.
Methoxide gives the ortho displacement probably due to less steric crowding.
Perhaps you can work out the mechanism?

[jarritos]

I believe i might have the general mechanism for them. The base deprotonates the O forming the methoxide then a simple sn2 reaction occurs replacing the F(better leaving group) with methoxide. This yields a molecule with the mw of 288 or 302 in the case of ethanol. Im not 100% on it but ill work on it some more tomorrow and post my results and mechanism.

[discodermolide]

I believe i might have the general mechanism for them. The base deprotonates the O forming the methoxide then a simple sn2 reaction occurs replacing the F(better leaving group) with methoxide. This yields a molecule with the mw of 288 or 302 in the case of ethanol. Im not 100% on it but ill work on it some more tomorrow and post my results and mechanism.

You seem to be on the right track.

[jarritos]

So the mechanism began with the deprotonation of the O by the base from the alcohol forming the alkoxide. This then displaces one of the F by SnAr reaction. This allows only for para and ortho positions of the methoxide. The ethoxide is para only because of the bulkier group.

[discodermolide]

So the mechanism began with the deprotonation of the O by the base from the alcohol forming the alkoxide. This then displaces one of the F by SnAr reaction. This allows only for para and ortho positions of the methoxide. The ethoxide is para only because of the bulkier group.

Seems ok to me.