Q. 4-4-6P - Organic Chemistry (Mcmurry)

Question

Prostaglandin ${\mathbf{F}}_{\mathbf{2}\mathbf{\alpha }}$, a hormone that causes uterine contraction during childbirth,has the following structure. Are the two hydroxyl groups $\mathbf{(}\mathbf{-}\mathbf{OH}\mathbf{)}$ on thecyclopentane ring cis or trans to each other? What about the two carbon chainsattached to the ring?

Step-by-Step Solution

Answer

Two hydroxyl groups on the cyclopentane ring are cis and trans to each other. Two carbon chains attached to the ring are trans.

Cis and Trans configuration

Cis configuration is when two groups are on the same face of the ring, and trans configuration is when the groups are on opposite faces. Both isomers are stable, and neither can be converted into the other without breaking and reforming chemical bonds.

Wedge bond and dashed bond

A wedged bond indicates a bond protruding out of the page, and a dashed bond indicates a bond entering the page.

Structures of Prostaglandin

Here the ring is in the plane of the page.

• Two hydroxyl groups are cis here as both are inside the plane of the paper.
• The two carbon chains are trans as one is out of the page, and one is into the page.