68. What product would be obtained for the following reaction? .
(A)
(B)
(C)
(D)
(E)None of the above

64. The carbon marked by a dot (•) is 13C isotope. Which structure below shows the correct position of the 13C in the product for the carbocation rearrangement shown above? (A) (B) (C) (D) (E)

65. Choose substituents X and Y (listed in order below) for the following compound so as to make a Z isomer.(A)(B)(C)(D)(E)

66. Rank the degree of unsaturation in each of the following compounds. I. Cholesterol , C27H46O II. DDT, C14H9Cl5 III. Prostaglandin E1, C20H34O5 IV. Caffeine , C8H10N4O2 (A) I ＞ III ＞ II ＞ IV (B) II ＞ IV ＞ I ＞ III (C) I ＞ II ＞ III ＞ IV (D) II ＞ IV ＞ III ＞ I (E) I ＞ IV ＞ II ＞ III

67. This cyclic carbocation has two sets of degenerate pi-molecular orbitals. Choose the correct order MO, s energies for this system? (A) V = I ＜ IV ＜ III = II (B) V ＜ IV = II ＜ I = III (C) III = II ＜ I = IV ＜ V (D) III = IV ＜ II ＜ I = V (E) V ＜ I = IV ＜ II = III

69. When 1-methyl-1-cyclohexene is respectively treated with the following reagent set, which will give the same product? (A) II, V (B) III, IV (C) II, III, V (D) I, V (E) I, III

70. Predict the outcome of the following sequence of reactions. (A) (B) (C) (D) (E)

71. The following substrate is a starting material in the synthesis of compounds having opioid activity. Show all products that would result from the reaction below. (A) I, II, III (B) I, III, IV (C) I, III, V (D) II, III, IV (E) II, IV, V

72. Predict the structure of the hydrolysis product. (A) (B) (C) (D) (E)

73. In order to synthesize the final product shown below, predict when should a protecting group be added and when should it be removed? (A) The hydroxyl group should be protected before step I and removed after step I (B) The hydroxyl group should be protected before step I and removed after step II (C) The hydroxyl group should be protected before step I and removed after step III (D) The hydroxyl group should be protected before step II and removed after step III (E) There is no need for a protecting group in this synthesis.

74. Which of the following Diels-Alder reactions has the largest reaction rate constant? (A) (B) (C) (D) (E)