Organic Chemistry: Concepts and Applications - Headley Allan D. 2020

Oxidation Reactions in Organic Chemistry
11.10 Applications of Oxidation Reactions to Synthesis

We have covered a number of different reaction types and now we are ready to make strategic choices about appropriate combinations of reaction types and specific reactions that can be utilized to synthesize target molecules. First, let us try and carry out the following transformation shown in Reaction (11-97).

(11-97)Image

As pointed out in previous chapters, one of the best approaches to determine the appropriate type of reactions and reaction conditions to carry out a particular transformation is that it is best to carry out a complete analysis of the target molecule focusing on the functional group and deciding the best reaction for its synthesis. The functional group in the target molecule is a ketone and as we have discussed in this chapter, a ketone can be synthesized by an oxidation reaction of an alcohol. Thus, an appropriate choice of reaction would be to convert an alcohol to a ketone, as shown in Reaction (11-98).

(11-98)Image

Of course, there are other possible oxidizing regents that could have been used, including Na2Cr2O7/H2SO4, PCC, and so on. Now that we have figured out the last step in this transformation, let us carry out a similar analysis to determine how best to synthesize the alcohol that is needed to make the target molecule. Reflecting on the reactions that we have studied, one type that comes to mind is an addition reaction involving akenes, more specifically, hydration of alkenes, but we will have to be careful since hydration can take place in one of two ways: Markovnikov or anti-Markovnikov addition. By looking at the structure of the starting material, the addition is an anti-Markovnikov addition, and the appropriate reagents are shown in Reaction (11-99).

(11-99)Image

Thus, the overall sequence of reactions for the transformation is shown in Reaction (11-100).

(11-100)Image

Note that an alternate way of writing this sequence of reactions is shown in Reaction (11-101), where numbers indicate the separate reaction steps in the sequence of reactions.

(11-101)Image

Problem 11.18

i. One of the constituents of turpentine is α-pinene, formula C10H16. Based on the reaction scheme shown below, give the structures of compounds A—D; show stereochemistry where appropriate.Image

ii. Show how to carry out the following transformations. Cleary show each step in your synthesis.Image