Q.29-55

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?



Step-by-Step Solution

Verified
Answer

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

1Significance 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.



2Dehydration of anti-elimination


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