Thiazole Formation – Thioamides


The thiol nucleophile for this reaction is just a tautomer of a thioamide. Thioamides are one of the few stable thiocarbonyl derivatives and can be made easily from conventional amides and P2S5 or Lawesson’s reagent


When a thioamide reacts with an α-haloketone: an interesting question arises. Both the nitrogen and the sulfur act as nucleophiles, so which one attacks the oxygen and which one attacks the halogen?

Carbonyl groups are ‘hard’ electrophiles- their reactions are usually charged controlled, and so react well with basic ‘hard’ nucleophiles. Alkyl halides are ‘soft’ electrophiles – their reactions are mainly under frontier orbital control and react best with large, ‘soft’, uncharged nucleophiles from lower down in the periodic table. So the ketone reacts with the nitrogen and the alkyl halide reacts with the sulfur.

Full mechanism of this reaction.


How useful was this page?

Click on a star to rate it!

Average rating / 5. Vote count:

No votes so far! Be the first to rate this page.

As you found this page useful...

Follow us on social media!

We are sorry that this page was not useful for you!

Let us improve this page!

Tell us how we can improve this page (in your own language if you prefer)? If you would like a response, please include your email address e.g. [email protected]

Provided by the