Topic 19: Protecting groups for alcohols

19.1What do the following abbreviations stand for in organic chemistry? TMS, TES, TBS, TBDMS, TBDPS, TIPS? Why all the varieties?
 
19.2When are silyl ether protecting groups needed?
 
19.3Why not just use a methyl ether? It would be a lot cheaper and greener.
 
19.4How many times in the synthesis of taxol by Robert Holton (Florida State Univ, 1994, Wikipedia) were silyl ether protecting groups used?
 
19.5In the figures of that Wikipedia article, how many reagents do you recognize?
 

Topic 20: Organometallic reagents: general reactions

20.1What three types are the only ones used to open epoxides?
 
20.2What is the limitation associated with the reaction of alkyllithium and alkylmagnesium halide reagents with esters and acid chlorides?
 
20.3What solution was developed to solve at least part of this problem?
 
20.4What problem remains to be solved?
 
20.5How could the reaction of organometallic reagents with CO2 be useful, particularly in aromatic chemistry? What is an example of a problem this solves?
 
20.6How could the reaction of organometallic reagents with H2O be useful, particularly in aromatic chemistry? What is an example of a problem this solves?
 

Topic 21: Organometallic reagents: 1,2- vs. 1,4- addition to α, β-unsaturated aldehydes and ketones

21.1The most important use of organocopper reagents is in relation to the addition to α, β-unsaturated aldehydes and ketones. What‘s the issue there, and how did the discovery of organocopper reagents provide a major new method for organic synthesis?
 
21.2The mechanism for 1,4-addition of an organocopper reagent to a ketone is not as simple as it might first appear. If you are interested, google ja00086a023, a paper in the Journal of the American Chemical Society (“JACS”) published in 1994 by Robin Smith, at the University of Otago, in New Zealand.
 
21.3In Mechanism 20.10 Part [2] your author proposes a sequence of protonation, with possible tautomerization following a mechanism presented in Section 11.9. What is tautomerization?
 
21.4Why is the mechanism of tautomerization presented in Section 11.9 almost certainly not the mechanism of tautomerization in this case? Can you suggest a more reasonable alternative mechanism?
 

Topic 22: Organometallic reagents: the formation of carbon-carbon bonds

22.1A major focus of this course will be on the formation of carbon-carbon bonds. Take a look at Appendix D to see where we are headed. How many carbon-carbon bond forming reactions does it show there from last semester? (There‘s one missing, by the way — see Table 7.4 in Section 7.8D.) And this semester?
 
22.2Why do you think carbon-carbon bond formation is so important — the stuff of half a dozen Nobel Prizes?
 
22.3How does focusing on carbon-carbon bond formation help in designing a synthesis such as those presented in the sample problems of this chapter or end of chapter problems 20.58-20.71?
 
22.4Smith 24.1A introduces an additional reaction of organocuprate reagents. What is that reaction? How could it be incredibly useful — almost too useful to the organic chemistry student — in organic synthesis?
 
22.5What are the practical limitations of this reaction? (think of two)
 
22.6How does this reaction solve the problem of both overalkylation and cationic rearrangement in Friedel-Crafts alkylation?
 
21 questions
472 questions for Organic II

472 Questions for Organic II

Dearest Student. This web page is a set of questions I call Detailed Intended Learning Outcomes For Organic Chemistry (Part II). Some time ago I asked myself, "Bob, what do you think are the key questions that you hope students will be able to answer after taking Chemistry 248 at St. Olaf College?" So here you have them. Some are very simple; some require more thought. All are good questions to be thinking about as you read, discuss, and master the practical aspects of organic chemistry. They are discussion starters and review tips. There are no answers here (though there are some clues). The questions are here to help you focus on what's important (to me, at least!) and organize your learning process. The questions are grouped into topics. Bite-size chunks. Take them a few at a time. Don't feast on them all at one sitting!

(preliminary version 2021.01.15 feeback: Bob Hanson)