After creating Molecule 23, Dr. Koreeda begins to feel light-headed and confused. He realizes that he been away from the Chemistry Building for too long and is now delirious, so he decides to ask a few law students, who happen to be there studying despite their disease, for help. When Dr. Koreeda explains his predicament, including what he is planning to make, the law students, glad to know a cure existed, inquire, “What type of reaction is this?” Dr. Koreeda answers them by talking about oxidation..

Question to be answered: What are other methods/reagents
 for achieving the same transformation and how would those
  methods/reagents compare with the one used in this article?

The starting molecule, Molecule 22, is a hemiketal. The reaction of Molecule 22 with TPAP is an oxidation reaction, turning the hemiketal (alcohol group attached to a ring with oxygen) into an aldehyde and ketone. TPAP is a strong oxidizing agent because it pulls electrons from the oxygen in the alcohol group.  TPAP is expensive, so in order to keep the catalytic reaction going without spending a lot of money, the co-oxidant NMO is added. This is known as the Ley-Griffith oxidation.  Hydrous reactions with TPAP with higher catalysts can turn an alcohol group into carboxylic acid. Oxidations of alcohols can occur with other reagents as well, such as pyridinium chromochlorate (PCC), Swern oxidation, and Jones’ reagents. All of these reactions create an aldehyde, carboxylic acid, or ketone.  However, some reactions work better than others, especially in comparison to TPAP/NMO.  Normally this reaction would not occur if it was a tertiary alcohol attached to a ring (without an oxygen atom), but because there is an oxygen atom present in the ring (thus it is a hemiketal) to donate electrons during the reaction, the oxidation reaction is possible.

PCC (Pyridinium Chlorochromate):
Similar to the reaction with NMO and TPAP, PCC is carried out in anhydrous organic solvents. PCC might be easier to use for an oxidation because it is not as expensive as TPAP and does not have to be maintained with another reagent. PCC stops at an aldehyde, so it could be more favorable if an aldehyde is desired without the possibility of turning into carboxylic acid. Also, chlorochromate is a strong oxidizing agent, so it can easily pull electrons from the alcohol group.  However, PCC was probably avoided due to its toxicity from Chromium (VI). There is also the byproduct of the reaction, CrO3 (Chromium (IV)), which sticks with pyridine and looks like black tar, which could be a difficult to remove. 

Jones’ Reagent:
A reaction with a Jones’ reagent is different in that water is involved the reaction (hydrous conditions). Because of water, although one may have an aldehyde at one point, in the end, the reaction will go all the way and the primary alcohol will turn into carboxylic acid. As a result, this is not a favorable reaction if one desires only an aldehyde, which is what the reaction in the article is. Similar to the problem with PCC, it is also toxic due to the presence of Chromium (VI), if using chromium trioxide.  A reaction with Jones’ reagents also occurs in acidic conditions, which could cause damage as well if handled improperly. Overall, it would not work well in this reaction because it would not give the desired product.

Swern:
This reaction is carried out in anhydrous conditions, similar to NMO and TPAP, and it is good for non-acidic conditions. It is non-chromium-based, so it is a “greener” method of oxidation. Also, dimethyl sulfide and oxalyl chloride after reaction with each other would be strong enough to pull electrons from the oxygen. However, Swern oxidation would not be a good method to use if one starts with a secondary alcohol because the product of the reaction will be only be a ketone and not the aldehyde. If one wants an aldehyde, then a primary alcohol is necessary. Thus, if a Swern oxidation were to occur on Molecule 22, the desired aldehyde would not result. 
In conclusion, Swern and Jones Reagent oxidation reactions would not give the desired products. In comparison to TPAP/NMO, TPAP/NMO would definitely be better to use. A reaction with PCC could give the desired product, but it is not as favorable as TPAP/NMO because PCC is toxic and gives an unwanted byproduct that could decrease yield and complicate workup. Thus, it is TPAP/NMO for the win!