the following reaction, expecting to get only the product

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1. (8 pts. each, 24 pts. total.) Undergraduate research assistant Sally Humdinger carries out
the following reaction, expecting to get only the product shown. Instead, she obtains two
products, A (major) and B (minor).

                                      CO2Et       LDA; CH3I                   CO2Et

                                                                        CH3

(a)    Draw out all of the H atoms of the expected product, and label equivalent H atoms with
      the same number and inequivalent H atoms with different numbers, as we did in class and
      on the homework.

                                              H        O        H   H
                                  H
                                                            O           CH3

                                       H          H   CH3

(b)    Predict the 1H NMR spectrum of the expected product, indicating the approximate
      chemical shift, integration, and multiplicity for each resonance that you expect to see. You
      can find a table of 1H NMR chemical shifts at the front of this exam. Note: You must
      answer the previous question correctly before you can answer this question.




(c)    Assuming that A is the expected product, use the spectral information below to
      determine the structure of Sally’s unexpected product B. You may also want to look at the
      intermediate enolate and think about what else it might do when it encounters CH3I.


    The MS of B shows a parent ion at 128 amu (same as A).
    The IR spectrum of B shows a very strong absorbance at 1726 cm–1 and a smaller but still
strong and sharp absorbance at 1662 cm–1.
    The 1H NMR spectrum of B shows δ 6.90 (dt, 1H), 5.76 (d, J = 15 Hz, 1H), 4.21 (q, 2H), 2.26
(dq, 2H), 1.30 (t, 3H), and 1.09 (t, 3H).
    The proton-decoupled 13C NMR spectrum of B shows δ 167.0, 144.7, 122.6, 51.3, 25.5, 15.0,
and 12.1.
                                                                                            2
2. (20 pts. total, 5 pts. each, graded manually.) Answer each of the following questions.

(a) Explain why indene is twenty orders of magnitude more acidic than indane.




                                 indene                     indane




(b) Explain why the reaction below is selective for the product shown, and the other
regioisomer is not obtained at all.

                                               HBr                        Br

                                          cat. peroxide




(c) Explain why the following reaction does not work as written, and suggest how you can
modify the reagents or the reaction conditions to obtain the product shown.

                                                     I            H3C           CH3
                                  LDA      H3C              CH3
             H3C      CO2Et                                                     CO2Et
                                                                        H3C




(d) Explain why the following reaction does not work as written, and suggest how you can
modify the reagents or the reaction conditions to obtain the product shown.

                                                                          CH3
                             H     LDA                CH3                          H
                H3C                        I                  H3C
                         O                                                     O
                                                                                               3
3. (30 pts. total. For each, 15 pts. for a correct answer on first two tries, lose one point per try
thereafter down to a minimum of 5 pts.) Draw a reasonable mechanism for each of the
following reactions.

(a)
                                                     O
                                          H3C             CH3

                                                –OEt                 H3C
                        O                                                          CH3
                                                                               O




(b)
                                  O                             O
                            HO
                                            CH3OH
                                      H                             OCH3
                                                H+
                                                                                        4
4. (15 pts. each, 30 pts. total, graded manually.)

(a) Design a synthesis of the following compound from neutral, metal-free starting materials
containing no more than four contiguous C atoms (plus any chosen from the reaction
conditions menu). Ideally, your synthesis would require five to seven steps, but that doesn’t
mean that a longer response would be incorrect.

                                               O
                                      H3C
                                                        O
                                      H3C




(b) Design a synthesis of the following compound from benzene or toluene and any other
neutral, metal-free starting materials containing no more than two contiguous C atoms (plus
any chosen from the reaction conditions menu). Ideally, your synthesis would require five to
seven steps, but that doesn’t mean that a longer response would be incorrect.


                                                   O



                                                            CH3