[kk1]

Hello,

I want really to know this way.

I am reading a book on organic chemistry. and it explains..

to block an α-position, it uses ii, BuSH, TsOH. and
to remove the one, it uses KOH H2O ethylene glycol, reflux.

I can understand the blocking. but I could not understand the removing with KOH H2O ethylene glycol, reflux.

Could not you teach me the mechanism just on the removing, this?



Thanks

[Dan]

Ethylene glycol is just a very high boiling solvent.

The deprotection is hydrolysis of the enol thioether, followed by a reverse Claisen.

Start with a Michael addition of hydroxide and see what you get...