69. For the following reaction sequence, which molecule is an expected major product? 

65. How many positive and negative peaks appear in the DEPT-135 and in the DEPT-90 spectrum of 2-methylpentane? (A) DEPT-135: two positive and one negative, DEPT-90: one positive (B) DEPT-135: three positive and two negative, DEPT-90: one positive (C) DEPT-135: three positive and two negative, DEPT-90: no signals (D) DEPT-135: two positive and three negative, DEPT-90: two positive (E) None of the above is correct

66. The Fischer indole synthesis is the reaction of phenylhydrazine with a carbonyl compound to give the corresponding indole. For the preparation of the following indole, what carbonyl compound is needed?  (A) I (B) II (C) III (D) IV (E) V

67. What is the major product obtained from the following reaction sequence?  (A) I (B) II (C) III (D) IV (E) V

68. Which of the following compounds can adopt a chair conformation in which there are no axial methyl groups?(A) 1,1-dimethylcyclohexane(B) cis-1,2-dimethylcyclohexane (C) trans-1,2-dimethylcyclohexane (D) trans-1,3-dimethylcyclohexane (E) everyone above have no axial methyl group

70. Which of these is NOT a useful method for the synthesis of 1,3-pentadiene?(A) 1,4-pentanediol + H2SO4 at 180o C (B) 2,4-dibromopentane + (CH3)3COK , (CH3)3COH at 75o C (C) 2,4-pentanediol + H2SO4 at 180o C (D) HC=CCH=CHCH3 + H2, Ni2B (P-2)(E) 1,4-dibromopentane + CH3CH2ONa , CH3CH2OH at 75o C

71. Which of the following series of synthetic steps could be used to carry out the transformation shown below? (I) NaOH, (II) heat, (III) CH3COCH2COOEt, EtONa, (IV) NaOH, heat, then HCl, H2O (A) I → II → III → IV (B) IV → II → I → III (C) III →IV → II → I (D) II → IV → III → I (E) None of the above

72. What is the name of the following reaction? (A) Mixed Aldol condensation (B) Mixed Claisen condensation (C) Mixed Dieckmann condensation (D) Mixed Michael reaction (E) Mixed Knoevenagel reaction .

73. Which of the following represents the HOMO of pentadienyl anion? 

74. Predict the major product for the following reaction sequence. (A) I (B) II (C) III (D) IV (E) V

75. The H-bonds formed in the tertiary structure of proteins can be differentiated from those formed in secondary structures. What is the major distinguishing factor? (A) The H-bonds in 3° structures are significantly stronger than those found in 2° structures. (B) The H-bonds in 3° structures are more random than those formed in 2° structures.(C) The H-bonds in 3° structures are formed by predictable interactions among the peptide backbone α-amine and α-carboxylate groups. (D) The H-bonds in 3° structures are formed by interactions involving the side chain R-groups. (E) Both B and D are correct.