University:
Amherst College
Course:
CHEM 221 | Organic Chemistry I
Academic year:

2023
Views:

243

Pages:

3
Author:

Dixie Roy

Chem 22 Homework set 11 No graded part this time. 1. Write a mechanism to explain each of the following transformations. Although these may seem completely alien at first, they all involve a series of familiar steps. Keep in mind that you only need to find a reasonable route to the product shown, not worry about the many other seemingly reasonable things that might have happened. One of these problems will appear on the April 22 exam (20 - 35 points), and another on the final. More importantly, they're excellent practice with condensations and other reactions. Once you get the hang of them, you'll be able to handle just about anything of the same ilk, and you may find that they're actually a lot of fun! (a) O O – HO H2O OH (b) H3O+ OEt O CO2H (c) NaOH O O H2O Ph O Ph Δ (d) O O + CO2Et NaOEt CO2Et EtOH H2C OEt OEt EtOCO CO2Et (e) O O O COOMe KOCH3 COOCH3 1. aq HO– 2. H3O+, Δ MeOCO O O (f) O O PPh3 Br NaH 2-cyclopentenone (g) (triethylamine acts as a mild base) CO2Et O + H2C OH CO2Et CO2Et EtOH Et3N O O 2. Suggest a synthesis of each compound below. Two of these will be on the April 22 exam (around 20 points each). In addition to the starting material specified, you may use only compounds in the chemical store (see attached page). (a) Start with malonic ester (EtOCO—CH2—COOEt). OH OH Ph O Ph CO2H H2N O O O O HO (b) Start with acetoacetic ester (CH3CO—CH2—COOEt). OH O O OH Ph CO2H Ph (c) Start with anything you want. You will probably need to do a condensation to start. O Ph Ph Ph O Chemical Store In addition to the compounds below, you may use any inorganic reagents, aqueous acids, or bases, and common organic bases like NaOEt, nBuLi, LDA, NaHCO3. alcohols organohalides carboxylic acids Br Ph OH Ph CH2OH Ph CO2H CO2H Br CO2H OH and any R–OH where R is a saturated alkyl group with 4 Cs or fewer Ph CH2Br Ph Br CO2H CO2H and any R–Br, RCl, or RI where R is a saturated alkyl group with 4 Cs or fewer CH3 CO2H HCO2H aldehydes H2C O O O O O ketones O cuprates Ph2CuLi O O Wittig reagents O CH2 Ph3P CHCH3 Ph3P CHCH2CH3 acetoacetic ester O CuLi and any R2CuLi where R is a saturated alkyl group with 4 Cs or fewer O OEt Ph3P (PhCH2)2CuLi 2 O O EtO O OEt malonic ester Ph3P C(CH3)2

Chemistry 22 Homework set 11

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