Organic Chemistry III
	Professor Carl C. Wamser
Chem 336 - Spring Term	Quiz 26

1. (2 points) Starting from L-glyceraldehyde-3-phosphate, show the product expected from NaBH4 reduction (the phosphate is unaffected), including the stereochemistry and designation of R or S for any stereocenters.

2. (2 points) Identify isoprene units in each of the following by clearly circling each one.

(two options on the right-hand compound)

3. (3 points) Complete the steroid structure on the right by adding all the rest of the chair forms and substituents as shown on the left.

4. (3 points) Polyketides are natural compounds containing alternating carbonyl groups, such as the one shown below.
Show a sequence of steps (mechanisms not required) whereby this compound could be created from acetyl coA.

(using malonyl CoA as the nucleophile in each step would be even more specific)