Organic Chemistry III
	Professor Carl C. Wamser
Chem 336 - Spring Term	Quiz 24

1.  (2 points)  DHA (docosahexaenoic acid) is one of the major fatty acids found in salmon oil.  It has 22 carbons (docosa) and 6 double bonds (hexaene) and is an omega-3 fatty acid.  Draw its structure.

2.  (2 points)  Write the basic four-ring structure of a steroid with all rings trans and six-membered rings in their chair conformations.

3.  (2 points)  Circle the isoprene units in the terpenes shown below.

4.  (4 points)  The dehydration step of fatty acid biosynthesis is proposed to proceed via an enol, as shown below.  For each step, indicate where you would place an acid and a base to facilitate each step.  Show electron-pushing arrows.