T   Organic Chemistry I Test Extra Synthesis Practice Problems Page 1: Synthesis Design Practice Page 2+3: Predict the Product Practice (including some that involve stereochemistry) Page 4: Cis/trans Stereospecific reactions: which recipe to use; which E or Z alkene to use Page 5: Recognizing cationic/anionic/radical reactions, and reasonable intermediates/first steps Page 6: Elements of unsaturation/hydrogenation problems; ozonolysis puzzle problems A Provide reagents for the following transformations Br OH Br O OH T Cl Br Br OH HO Br OH OH O T O HO HO       B Draw the major product for each of the following reactions or reaction sequences You needn’t bother T to show side products or minor products For chiral molecules that are racemic , you needn’t draw both enantiomers BE CAREFUL TO SHOW THE CORRECT ORIENTATION, AND THE CORRECT STEREOCHEMISTRY IN CASES WHERE STEREOCHEM IS FACTOR (3 points each) H 2SO 4, heat OH Br NaOH Br NEt 10 HBr 11 HBr, peroxides T 12 HBr, peroxides 13 NaOCH H 2O, H + 14 Hg(OAc) 2, H 2O 15 NaBH Hg(OAc) 2, H 2O 16 T NaBH H 2SO BH 3-THF 17 NaOH, H 2O2 BH 3-THF 18 19 NaOH, H 2O2 Hg(OAc) 2, CH 3OH NaBH Note: explicit stereochemistry must be drawn The enantiomer would have been equally acceptable     HBr NaOCH 20 T Br 21 Br 2, H 2O 22 Note: explicit stereochemistry must be drawn The enantiomer would have been equally acceptable This principle will apply for any of the reactions producing two chiral centers Problems 23-32 Br 23 Br 2, H 2O 24 Cl2 25 Cl2 26 PhCO 3H T 27 PhCO 3H 28 Ph 29 Ph CH 3CO 3H, H 2O CH 3CO 3H, H 2O 30 OsO4, H 2O2 31 Ph OsO4, H 2O2 T 32 O3 33 Me 2S O3 34   Me 2S       C Draw the alkene that would product the products shown Make sure to make your drawing clear whether the starting alkene was E or Z Cl T Cl2 Ph 35 Cl OH Br 2, H 2O 36 Br OH CH 3CO 3H, H 2O 37 OH OH OsO4, H 2O2 38 OH T BH 3-THF H 3C H NaOH, H 2O2 Ph 39 OH O PhCO 3H H 3C 40 CH2CH O3 Me 2S 41 D What reagent(s) would you use to conduct the following transformations? T OH Ph Ph 42 OH CH Ph 43 H 3C OH Ph OH   E Recognizing whether reaction mechanisms should be cationic, anionic, or radical; whether intermediates should be cationic, anionic, or radical; and recognizing what could be reasonably involved in the initial reaction step T 44 The transformation shown is common in many biological systems Which of the following statements is definitely, absolutely false? a The first step in the mechanism probably involves protonation of the carbonyl oxygen b The overall reaction involves an addition reaction c The mechanism is probably radical in nature 45 For the transformation shown, which of the following statements is definitely, absolutely false? a The first step in the mechanism probably involves protonation of a carbonyl oxygen b The overall reaction involves a substitution reaction c The mechanism is probably anionic in nature d The first step in the mechanism involves ethoxide anion grabbing a hydrogen T T 46 Shown is a reaction, and some possible intermediates along the mechanistic pathway Given the reaction conditions shown, which of the following statements is true? a Structures A and B might be plausible intermediates; structure C definitely isn’t b Structures A and C might be plausible intermediates; structure B definitely isn’t c Structures B and C might be plausible intermediates; structure A definitely isn’t d Structure A might be a plausible intermediates; structures B and C definitely aren’t 47 Shown is a reaction, and some possible intermediates along the mechanistic pathway Given the reaction conditions shown, which of the following statements is true? a Structures A and B might be plausible intermediates; structure C definitely isn’t b Structures A and C might be plausible intermediates; structure B definitely isn’t c Structures B and C might be plausible intermediates; structure A definitely isn’t d Structure A might be a plausible intermediates; structures B and C definitely aren’t O H+ H2O O HO O O OH O NaOEt O OEt OEt BrCH OH NMe2 + HNMe H OH O A CH O H+ H2O NMe O Ph B   OH NMe H NaOMe OCH3 MeOH C O O Ph OCH3 Ph O Ph A OH OCH3 Ph H 3CO O O Ph OCH3 OCH3 B C Ph   F Elements of Unsaturation/Hydrogenation Problems For each problem there will be multiple satisfactory solutions T 48 Provide a possible structure for a compound with formula C5H8, given that it reacts with excess H2/Pt to give C5H10 Answer must show one alkene and one ring (Other structures also meet that requirement) H2/Pt test proved alkene EU=2 originally So the other EU must be ring 49 Provide a possible structure for a compound with formula C6H8, given that it reacts with excess H2/Pt to give C6H12 Answer must show two alkene and one ring (Other structures also meet that requirement) H2/Pt test proved alkenes EU=3 originally So the other EU must be ring 50 Provide a possible structure for a compound with formula C8H10, given that it reacts with excess H2/Pt to give C8H14 Answer must show two alkenes and two rings (Other structures also meet that requirement) H2/Pt test proved alkene EU=4 originally So the other two EU must be two rings 51 Provide a possible structure for a compound with formula C6H8, given that it reacts with excess H2/Pt to give C6H12 Answer must show two alkene and one ring (Other structures also meet that requirement) H2/Pt test proved alkenes EU=3 originally So the other EU must be ring T G Ozonolysis: Draw starting chemicals that will undergo ozonolysis to produce the products shown In some cases there may be more than one satisfactory answer O3 52 O H Me 2S O O H O3 Me 2S H 53 T Any of three answers O O3 Me 2S 54 O H H O H H O3 55 Me 2S O + O O O + H H O + H O   ... 3OH NaBH Note: explicit stereochemistry must be drawn The enantiomer would have been equally acceptable     HBr NaOCH 20 T Br 21 Br 2, H 2O 22 Note: explicit stereochemistry must be drawn The... needn’t draw both enantiomers BE CAREFUL TO SHOW THE CORRECT ORIENTATION, AND THE CORRECT STEREOCHEMISTRY IN CASES WHERE STEREOCHEM IS FACTOR (3 points each) H 2SO 4, heat OH Br NaOH Br NEt 10