The reaction of aldehydes with 1,3-dithiacyclohexane, in the presence of Lewis acids, produces 1,3-dithianes that have hydrogens that can be subtracted with strong bases, forming the 1,3-dithiane anion. These anions are very good nucleophiles and react with a wide range of electrophiles.
Let's see how to obtain 2-butanone from ethanal.
![synthesis 13 days 01](/images/stories/organica-ii/compuestos-difuncionales/sintesis-13-ditianos/sintesis-13-ditianos-01.png)
Mechanism:
Stage 1. Formation of 1,3-dithiane
![synthesis 13 days 02](/images/stories/organica-ii/compuestos-difuncionales/sintesis-13-ditianos/sintesis-13-ditianos-02.png)
Stage 2. Formation of the 1,3-dithiane anion.
![synthesis 13 ditians 03](/images/stories/organica-ii/compuestos-difuncionales/sintesis-13-ditianos/sintesis-13-ditianos-03.png)
Stage 3. Nucleophilic attack
![synthesis 13 ditians 04](/images/stories/organica-ii/compuestos-difuncionales/sintesis-13-ditianos/sintesis-13-ditianos-04.png)
Stage 4. Hydrolysis of the thioacetal
![synthesis 13 days 05](/images/stories/organica-ii/compuestos-difuncionales/sintesis-13-ditianos/sintesis-13-ditianos-05.png)
Other examples:
![synthesis 13 days 06](/images/stories/organica-ii/compuestos-difuncionales/sintesis-13-ditianos/sintesis-13-ditianos-06.png)