Question

In step 7 of fatty-acid biosynthesis (Figure 29-5), dehydration of a b-hydroxy thioester occurs to give trans-crotonyl ACP. Is the dehydrationa syn elimination or an anti elimination?

Short answer

The dehydration of syn elimination or an anti-elimination can be predicted.

Step-by-step solution

Significance of stereo chemistry

There are three elimination reactions occurring in biological pathway. There is more common in elimination of conjugate base mechanism.

The substrate is alcohol than alkyl halide and H atom can be removed adjacent to carbonyl group. 3-Hydroxy carbonyl compound can be converted into unsaturated carbonyl compounds using elimination reaction.

The first reaction is the synthesis of fats.

Dehydration of anti-elimination

The dehydration of anti-elimination with each of carbon carbon bond i.e., H and OH form opposite sides.